Buttons become greyed out.
Noticed this one previously, but still happens.
Have a category with a few pages worth of topics (I use Pagination), move a number of topics from page 1 of the large category to another category, then press F5 once those topics have moved.
For me, at this point, the Share, Topic Tools and Ignore Buttons are all greyed out and can't be clicked. The only workaround for this is to (via ajax) go to another page, then back. A hard refresh doesn't always solve it.