Hi! Apologies for the delay, I missed this thread somehow :( I have noticed loading issues in the past, and have tried my best to resolve all of them. The most recent version added a new safeguard for track load failure, which was pushed in February (Only the online editor was updated), if you used a version of Scritch before that, I’d try it again. In any case, I can’t seem to reproduce the issue myself with your example page. I don’t have an ios device to test on, but desktop and mobile firefox/chrome all work fine. If the issue isn’t resolved with the new version, I have to suspect it’s an issue with (ios?) safari. With your troubleshooting on windows 8.1 firefox, that seems similar to previous loading issues I’ve since resolved (on my end, at least). If that persists, then I’m not sure what the issue may be.
Not sure if this is possible for ios safari, but if you open the browser’s devtools and see any errors as the tracks attempt to load, that may be helpful.