User blog comment:Rupert Giles/Global Navigation Update/@comment-452-20141202163302/@comment-452-20141203005542

Thanks for the info, it looks like I'm in group A, but I'll try clearing my cookies. (Edit: I tried, but clearing my cookies didn't help.)

No, that isn't the issue I'm referring to, as there is no "show changes" button when editing a blog comment.

See tickets #168983, #148724 and #137367 for info about the bug.