>'wrong Captcha' despite about a dozen attempts.
I dunno what can be the problem, I'm passing it on. Also gonna make tests, perhaps broke something recently.
>deleting the post worked fine.
Deletions don't need captcha.
>Related question
As long as one post with the file is up, it isn't an orphan, so won't get deleted. All orphaned files after a while (about two weeks) get scrubbed from the db automatically. Global staff also checks uploaded files daily (couple of times a day) and we scrub the cp from the db, no matter if orphaned or not (so we should catch cp spam that we don't notice getting posted).