When reviewing diffs for a PR in Firefox, I often find that clicking on a different file may not change the diff. It continues to show the first file diff. It works fine in Chrome however.
I think it may have to do with having spaces in the path of a file that has changed. If I click a file that has spaces in the path it shows me the diffs for the first file. If I click on a file that does not have spaces in the path it works correctly.