Reduce repository size caused missing commits in merge requests

Hi,

I’m running GitLab self-managed and I tried to reduce the size of a repo by following this guide:
https://docs.gitlab.com/ee/user/project/repository/reducing_the_repo_size_using_git.html

Everything seems to work as expected (the size was reduced and the master branch has all the correct changes), but the merge requests that were created after the changed commits does not have any changes any more:

The log just says 404 Not Found. Is this the expected behaviour when running repository cleanup or have I done something wrong?

New merge requests seems to work as as expected.

Thanks for the help!