I’m having the same problem. I tried multiple times with both Firefox and Chrome and after waiting 24 hours, I was still stuck on the endless “loading” screen.
I’m having the issue as well on Google Chrome. I only attached a screenshot and a 115kb log, and I’ve been stuck on the loading screen for ten minutes and counting. I tried to submit without attaching a log, and the page wouldn’t allow it.
EDIT: I reattempted the submission in Microsoft Edge and it worked after a few seconds.