I've been experiencing this now since the beginning of this year that when I upload something it either doesn't show up in the uploads tab (blank thumbnail) or it never gets processed. Some uploads just stay in limbo it seems.

I contacted them a few times and they swiftly pushed some files through but not all of them.

I asked them to delete the files that didn't get pushed through but nothing happened. I can't delete them.

Did anyone else experience this?

Yes I'm also having similar issues. It seems their upload process is very slow and sloppy these days. Unfortunately that doesn't bode well for the future of this low earner site.