Same experience with Firefox, seems to require Chrome. There is a security-related error in the console.

It currently breaks in Firefox private mode because I use the Cache APIs to try and prevent downloading the same file more than once, but Firefox disables the Cache APIs in private mode in a way I can't easily detect up-front. I'd love suggestions for a workaround or fix.

https://developer.mozilla.org/en-US/docs/Web/API/Cache

Ah! That's what got me. Private mode is my default. I can confirm that I get it working in Firefox outside of private mode. Thanks :)

Firefox is such a pain to me as a web dev who does a lot of WebGL and Web Audio API work. Even CSS and SMIL animations can get funky. It’s not nearly as bad as Safari but it’s harder to swallow due to how small the user base is relative to the amount of time it sucks out of my life.

Works with Firefox in Fedora

works in Firefox+macOS