Review workflows let a reviewer accept, fix, or reject submitted annotations so that only high-quality data leaves your project. This is a Label Studio Enterprise feature: the review stream, the Reviewer role, and reviewer assignment do not exist in the open-source Community edition. If you are on Community and looking for review, that is expected behavior, not a bug.

Most review problems come down to a few causes: the reviewer has the wrong role, the review stream is empty because of how it is gated, tasks were never assigned, a Data Manager filter is interfering, or there is confusion about what Accept/Reject actually do. Work through the section that matches your symptom.

A task moves through three review-related states: Annotating → Needs Review → Done. Almost every issue below is about why a task is not moving between those states as expected. Review options are configured under Settings → Review. See Project settings (Enterprise) and Review annotations.

Review options are missing entirely

If you (or a team member) cannot find a Review tab in project settings, a review stream, or any accept/reject controls:

1. Confirm you are on Label Studio Enterprise. Review workflows are Enterprise-only. Community/open-source editions have no reviewer role and no review stream.
2. Confirm the user's role. Reviewing is only available to users with the Reviewer role or higher (Manager, Admin, Owner). Annotators cannot open the review stream. See Manage roles and users.
3. Confirm the role is set at the right level. A role granted at the organization level is not the same as the role a user holds inside a specific project or workspace. Verify the user's role on the actual project.

A reviewer's queue is empty ("no tasks to review")

This is the most common report: a reviewer starts reviewing and immediately sees that there is nothing to review. The review stream only surfaces tasks that have reached the Needs Review state, so an empty queue is almost always gating, not a fault. Check these in order.

1. Are there submitted annotations at all? The review stream shows annotations, not raw tasks. If annotators have not submitted anything, there is nothing to review. Confirm submitted annotations exist in the Data Manager.
2. Is Show only finished tasks in the review stream enabled? When this setting is on, a task only becomes eligible for review once it has met its annotation requirement: - In auto distribution, that means the task has reached the Annotations per task (overlap) threshold. - In manual distribution, that means all assigned annotators have submitted an annotation. - Skipped tasks generally do not count toward meeting the minimum. A project waiting on one more annotation (or on a skipped task) will show an empty review queue until the requirement is met. If you need reviewers to start as soon as a single annotation exists, turn this setting off so a task is eligible after one submitted annotation.
3. Is Review only manually assigned tasks enabled? When this is on, a reviewer only sees tasks they have been explicitly assigned. If no one assigned them tasks, their queue is empty. Note the important side effect documented for this setting: a task can move from Annotating straight to Done if this is enabled and no reviewers are assigned — meaning tasks are never reviewed at all. If you expected everything to be reviewed, either assign reviewers or disable this option.
4. Check Review Sampling. This controls how many eligible tasks actually need to be reviewed and can send some tasks straight to Done without appearing in the stream. If fewer tasks show up than expected, verify the sampling configuration.
5. Has the reviewer already reviewed everything eligible? Once all annotations matching the current settings have been processed, the stream is correctly empty.
6. Are Data Manager filters or the active tab hiding tasks? See the next section — a filter is a very common cause of "review is no longer possible."

Tip: As a Manager/Admin, open the Data Manager and check the annotation and review columns. If tasks show submitted annotations but a review state of Needs Review with no reviews, the annotations exist and the issue is assignment, the "finished task" rule, or sampling above.

"Review is no longer possible" after applying a filter

Reviewers frequently build a queue with a Data Manager filter (for example, Agreement < 100 combined with Reviewed is no to catch low-agreement work). Two things commonly go wrong:

1. OR vs. AND logic. Confirm the filter group is set to match all conditions (AND), not any (OR). With OR, adding one more value widens the match and, combined with the review stream's own gating, can leave the queue empty or pull in tasks that do not belong. A reliable reviewer-queue combination is: - Reviewed is no AND <your field> contains/is <your value>
2. Reviewers may not have the Reviewers/Reviewed columns by default. To reduce bias, reviewers do not always have access to review-related columns and filters. If a saved filter relies on a column the reviewer cannot operate, it can behave unexpectedly for them. Reviewer Data Manager access is controlled under Settings → Review → Data Manager.
3. A filter that used to work and now throws an error. If a previously working review filter suddenly errors (a red banner, an invalid-filter message, or a blank/spinning review view), rebuild it one condition at a time to find the trigger, and report it — filter-on-review-status regressions have occurred and been fixed on the backend before, so support can confirm quickly whether you have hit a known issue. Include the exact field, operator, and value, plus whether you are on Cloud or self-hosted (and the LSE version).

Assigning reviewers, and assignments not appearing

Reviewer assignment is a manual routing tool: you pick tasks and assign specific reviewers to them.

To assign reviewers:

1. Open the project's Data Manager.
2. Select the tasks you want to route (use the header checkbox to select everything matching the current filter).
3. Use the assignment action to Assign Reviewers, then choose one or more reviewers.

See Assign reviewers/annotators to tasks.

If assignments do not appear or do not take effect:

1. The user does not appear in the reviewer picker. They are not a project member with a reviewer-capable role. Add them to the project (or workspace) and give them the Reviewer role or higher, then reassign. See Set up a project and Manage users.
2. The assignment saves but the reviewer still sees nothing. Confirm the assigned tasks have submitted annotations and meet the "finished" rule above — assigning a reviewer to a task that has no reviewable annotation yet will not populate their queue. Also confirm Review only manually assigned tasks matches your intent.
3. You expected assignment to be automatic. With Review only manually assigned tasks off, reviewers pull eligible tasks from the shared pool without per-task assignment. If you want that behavior, do not assign every task by hand — just verify the routing under Settings → Review.

Accept, Fix & Accept, and Reject behave unexpectedly

When reviewing, a reviewer has three actions (see Review annotations):

• Accept — the annotation is correct.
• Fix & Accept — the reviewer corrects the annotation, then accepts it. The agreement between the annotator's version and the reviewer's fix feeds the annotator's performance score.
• Reject — the annotation is incorrect.

What Reject actually does is governed by Settings → Review → Reject Options. This is the source of most "the task came back" / "the annotator can't see my rejection" confusion:

• Requeue rejected annotations back to annotators — on reject, the annotation is reassigned back to the annotator to redo. The task will re-enter the review stream after they resubmit. This loop ends only when the annotation is accepted, so rejected tasks reappearing is expected, not a duplicate bug.
• Remove rejected annotations from labeling queue — on reject, the annotation is not returned to the annotator. Note that Remove also marks the annotation as cancelled/skipped (surfaced in Data Manager columns, dashboards, and as was_cancelled: true in the API).
• Allow reviewer to choose: Requeue or Remove — the reviewer sees Accept, Remove, and Requeue and decides per annotation.

Related points of confusion:

1. "Rejected annotations don't go back to the annotator." That only happens with Requeue selected/enabled. With Remove, they do not return. If you are following the general reviewing guide, note that in the base flow a rejected annotation is not returned to annotators unless the project is configured to requeue it.
2. "A task shows submitted annotations but is not marked Done." Check the reviewing rule: Task is reviewed after one annotation is reviewed (accepting one is enough) versus Task is reviewed after all annotations are reviewed (the reviewer must accept or reject every annotation on the task). With the "all" rule, one unreviewed annotation keeps the task in Needs Review.
3. "A rejected annotator was unexpectedly unpaused." When a project requeues rejected tasks, rejecting an annotation can return the task to a paused annotator. This interaction has been adjusted in past releases — if behavior looks wrong, check your LSE version.

Review timing questions from annotators/contractors

Annotators (including external contractors) sometimes open a ticket asking why a completed assessment or task has "not been reviewed" for days. Clarify expectations:

• There is no platform-wide review SLA. When and whether annotations are reviewed is entirely controlled by the project's reviewers, managers, and review settings in the organization that runs the project.
• A project showing 100% annotated does not mean it has been reviewed — those are different states (Done annotating vs. reviewed).
• Direct the annotator to their project manager/administrator or the organization that invited them; HumanSignal support cannot see or act on another organization's internal review queue.

Review stream configuration checklist

When behavior differs from expectations, verify these under Settings → Review (Project settings, Quality workflows):

• Reviewing Options — how many annotations must be reviewed for a task to move from Needs Review to Done (one vs. all).
• Show only finished tasks in the review stream — whether the annotation requirement must be met before a task is eligible.
• Review only manually assigned tasks — whether reviewers must be assigned tasks (and the "no reviewer ⇒ straight to Done" side effect).
• Review Sampling — how many eligible tasks actually require review, and stream ordering (By Task ID or Random).
• Reject Options — Requeue, Remove, or let the reviewer choose.
• Reviewer instructions — enable Show before reviewing to surface instructions when the reviewer enters the stream.
• Data Manager — which columns/filters reviewers can use.

Change one setting at a time and re-check the reviewer's stream so you can attribute the effect.

Still stuck?

If review options, assignments, filters, or accept/reject behavior are still not working after the steps above, please submit a ticket with:

• Your Label Studio Enterprise version and whether you are on Cloud (SaaS) or self-hosted.
• The affected project ID and the reviewer's role at both the organization and project level.
• A screenshot of the project's Review settings and of the reviewer's empty/unexpected stream or filter.
• A sample task ID that should be in the queue but is not, including its annotation and review state from the Data Manager.
• For a filter problem: the exact field, operator, and value, and whether the group is set to AND or OR.

These details let support reproduce the routing and confirm whether it is a configuration issue or a defect.