Answered my own question by trying one more time... so yes you can and it works great 👍🏼

So @joelbaudin, how did you do it? I just completed a task using "/done..." and uploaded an image to the @wipbot chat a few seconds after (because I heard that's how it works) but it didn't show as part of the done task...

@alexanderkluge I haven’t done it by using the /done command (only via @wipbot + space and then selecting the task) but I cant imagine it should matter.
But I’ve noticed the @wipbot has been slow yesterday and this morning (CET) so perhaps that’s the reason for it not working?
Make sure you upload an image and not attach it as a file, I did that a couple of times...