Hi ItsRogueBen!
Sorry I didn't see your last post. I would have directed you to capturing a Console Log (Chrome, Firefox) and filing a Help Center Request. That's the best way to get dev attention. The forums are mostly community help.
Here are a couple of things you can try, though.
1) Try a private browsing window. If it works there, odds are it is likely an extension conflict or a cached data/bad cookie issue.
2) Try a different browser. If it works there, it is likely a browser setting issue or one of the previous problems.
3) Make sure you are using a supported browser, either Chrome or Firefox.
If you get it to load using one of the options above, try disabling extensions till you find the culprit. There is some anecdotal evidence that ad blockers or password handlers can cause problems. Try turning that off temporarily, or whitelisting the Roll20 site. You can also delete cache and cookies. Although you can search for just Roll20 cookies in your browser, it's probably more effective to delete them all.
Finally, which character sheet are you using? Is it an official Roll20 sheet?