As luck would have it, I’ve been one of those whose experienced the issue and did chase through the dev tools
There’s no console error.
In fact, there’s no iframe for the extension in the streamer’s main page. So it’s not that the extension fails to appear, it’s that it’s iframe that holds it never loads in the first place, suggesting its internal JS never even runs.
Again, there’s not even an extension taskbar icon. *
( * Actually it’s a little stranger than that: occasionally – but not always – there IS an extension taskbar icon, but it only lasts a split second before disappearing. If the problem were a result of JS coding , I’d expect the extension’s iframe to persist and fail to render, and an error to appear and persist in the console.)
I suspect Twitch does not have code to remove an iframe from the streamer’s DOM after loading. It seems more likely the iframe never loaded to begin with.