We're having the exact same issue with a survey form that is being called from a Field Maps map. When a user clicks on a hyperlink in a Field Maps popup, it fires up an inspection report in Survey 123 using a custom URL scheme. It was working a week ago, and now when we try it, it successfully opens Survey123 but gets stuck in the loop of "Unpacking", "Downloading thumbnail", "Downloading", until it times out and gives the 'Error Unpacking' message.
I've tried unistalling and reinstalling the app and clearing the cache, but it hasn't helped. We have the same issue on iOS and Android.
Any luck with your issues Josh?
Thanks,
Brendan