Merge Request comments have stopped appearing for the whole project

For example, consider the private repository https://gitlab.com/musedev/muse/merge_requests/192

Comments are not appearing even though some MRs have 10 notes attached. These comments were made by a bot and are likely somewhat long (thousands of bytes)... but I wouldn't know for sure because I can't see them.

I also experienced this issue with gitlab-ee but was unable to provide a reproduceable test to the team, hopefully now being on gitlab.com makes that unnecessary.