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.

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.