You would get an error message if you go over the 512KB, it's not that.
Mine won't upload either, and I'm way under the 512KB as a test. It does show a blank box as though it uploaded something, but the actual logo isn't showing. Day 1 hiccups is all, I'm sure they'll clear it up soon.
EDIT: I'm also seeing that I cannot see the helmets or jerseys in the UI. I'm using Google Chrome, may be a browser issue or something technical on our end. Will try a few different browsers to test.
Same issue here and I'm on edge, if you figure out a way to get them to load, it'd be great if you could let me know (:
