Huh. I'm not sure what happened, but maybe the infinitely loading page in both browsers finally worked somehow?
Deleted one, uploaded new one, works fine now, even 7z. No Idea what was that... solved, I guess?

Sure. Though it's too large to attach in here, so here's the link: https://dropmefiles.com/EJEOS

Used to work just fine, no problem encountered with any previous soundbank uploads to this point.
Anyway, trying to upload the zip file now, so far still loads for a very long time and shows no signs of stopping.
¯\( =_=)/¯
Edit: After the long wait, the page just froze now.

What the title said. Trying to upload a 7z archive, filled in all the needed fields and pressed Send, the page just starts loading and never stops.