This question, closed yesterday, was bumped by its OP requesting reopen votes. I decided to roll back the edit (I know this doesn't 'unbump' it but that's not my point), but it seems the formatting has gone kaput and no longer works. However, if I click on 'edit', the formatting shows up OK in the editor's live preview. Resaving the edit doesn't fix the problem though.
This is my first rollback on a closed question, and it's also the first time I see this error so I'm wondering if it has anything to do with its closed status.
EDIT: R. Bemrose chipped in with an extra newline and the formatting is back. But I did experience the formatting bug when I rolled it back before that.
EDIT 2: waffles inadvertently uncovered this issue here on Meta, for this open question, so it's nothing to do with closed status then.
EDIT 3: gah, it just hit me again on another open question. I think SO doesn't like me rolling back edits anymore. Fixed it also by adding blank lines. I also edited the question title because it doesn't just affect closed questions.
EDIT 4: looks like this is affecting answers too, thanks Shog9.