Pull Request labels are sporadically working on multiple repos

[veesanam]

Steps to reproduce:

Open a PR and try to add/edit/delete labels
Expected result:

If a PR is labeled, you should be able to see and edit its labels
If a PR is not yet labeled, you should be able to add labels to it

Actual result:
The PR labels control is sporadically missing on either new or existing PRs
Earlier today, PRs with existing labels did not allow them to be managed at all

Please help here