Diff showing "0 changed files, nothing to merge" on large merge request

Created by: ascii-soup

We have a new git repository with hundreds of branches, imported from SVN.

Some of these branches are fairly long-running (6 months+) and have had the old SVN trunk merged into them a number of times.

When creating a merge request for one of these branches (branch -> master), I noticed that the "diff" tab on the main page of the merge request stated:

Showing 0 changed files

Nothing to merge

Now there is definitely code to merge; the merge request contains 54 commits and a large number of changed files.

Is this a bug? Is the diff deliberately "denied" because there are too many files/commits?

If you need any additional info, or want me to try anything, I'm happy to help.

This is proving to be a deal-breaker at work, which is a shame!