The previous really strange Google (Team Drive) permission failure I recall here ended like this:
Maybe yours (while strange) can be studied in Google web UI. Do the file details show creator?
above is from January, but the latest GUI here doesn’t show what created it now. Does yours?
I get nervous about relying on full access because Google had been planning to take it away…
It seemed to me like this would break lots of use cases, which might be why it’s not done - yet.
Enhancing security controls for Google Drive third-party apps