Turns out this was related to a isReady check function in our JavaScript that would not fire properly in the twitch webview. When the check failed it would hide the app, resulting in the white screen I was experiencing.
Would be cool if there was some kind of stack tracing added to the Twitch Extension Dev Rig for problems like this, the check functions correctly on other browsers just not in the Twitch webview, but figuring that out was very difficult/time consuming.