Hi Harry!
Did you check if it's working in Android? Just to know if the issue only affects iOS or it also affects Android.
I was thinking that maybe Google Docs doesn't "like" being embedded in the app (which uses a special protocol, not http), but then I guess Google Slides wouldn't work either.
I'll send you a private message with the details about how to send us a backup or give us access so I can take a look
Cheers,
Dani