Merge request comment disappears when project forked from group repo into personal repo

Summary

Merge request comment disappears when project forked from group repo into personal repo

Steps to reproduce

1. Create a group.

2. Add a project to that group.

3. Add a file to the project and commit/push it.

4. Fork the project to a personal repository.

5. Add a file to the forked project and commit/push it.

6. Comment on the commit you just did.

7. Create a merge request to merge the commit to the group project master.

8. Open the merge request and try to reply to the comment from earlier.

What is the current bug behavior?

The customer sees slightly different behaviour than I do, in which case the reply will disappear with the following response:

{"commands_changes":null,"valid":false,"errors":{"note":["can't be blank"],"project":["can't be blank"],"noteable_type":["can't be blank"],"noteable_id":["can't be blank"],"author":["can't be blank"]}} )

Using Brave browser on gitlab.com the comment simply disappears with no error when I reproduce the issue.

What is the expected correct behavior?

The comment should save and be viewable.

Output of checks

This bug happens on GitLab.com