In different situations, you can find the Labeling UI is broken entirely or partially, which could include the following issues:
- Buttons are not clickable
- Interface clutter or UI elements clashing
- Errors while scrolling the page
- Jittering
- etc.
If you only see that in the specific projects, it can be the problem with your labeling configuration and custom styles. Check to see if you've recently removed a field from your labeling configuration that had previously been filled in an annotation.