Given that this seems to be happening to the same people repeatedly (I'm looking at you Mnem) and not to just everybody at random, can I suggest that the people who've experienced this post what combination of browser/version/platform that they are using? It has the flavour of being something like a change in platform javascript behaviour, perhaps tied to a particular recent version/update. If my hypothesis is right we should see some commonality between the setups of people that it's happening to, if it's wrong then we won't.
Nahhhh... it's happening to lots of people. You just notice it more with me because I'm a heavy abuser of visual aids; goes with the territory being the class clown.
I've been trying to find a process which ameliorates the issue; right now I'm doing this:
I make sure I finish the longish process of editing the text of a pic-laden post and click "Review" just before adding pics to eliminate the possibility of a "There are new posts" red flag ducking up my file uploads; this has been going on since long before this latest SMF indignity.
BTW, I have confirmed that it isn't just image files which get borked; I had a .pdf wind up in limbo the same way not too long ago.
Also, I make sure to:
Resize my pics to ~300k or less
Upload 3 or less at a time, and
Wait 10 seconds after the last pic is "uploaded" before I click "POST" or "SAVE" so the process completes as quickly as possible.
This ties in (I think) with the notion gnif proffered a while back that the issue is related to lag in propagation between servers; at first I thought it might have been because I sortof straddle 2 transatlantic trunks here in Toronto, but extensive trial & error found no correlation with whether I was using my VPN (server in New Jersey) or not.
When I DO get a borked pic, I try to fix it by just adding that pic again and linking to the new pic rather than deleting the faulty pic and replacing it. This seems to lessen the likelihood that fixing a post will then bork another older post in the thread. It SEEMS to; that may just be confirmation bias.
Good hunting, gnif!
mnem