There was no error at all. the files just remained where they were.
To follow up on this (as I've made some headway)... Originally I wanted sonarr to transfer files to /video/tv shows/* (the shared folder created by Video Station). I could never get the transfer to work, so I added a /tv shows folder under /docker/sonarr/tv shows (that worked).
But I never liked that... so this week I created a shared folder "media" and moved my files from /video/tv shows (subsequently I uninstalled Video Station, and deleted the "video" shared folder.
I assigned "user1" as the owner of /media/tv shows/* and updated the sonarr docker to this path. Success... files transferred... BUT... I was using PUID/PGID for "admin1" under sonarr... and I edited this to PUID/PGID for "user1"
Guess what? No transfer.
Next, I added PUID/PGID for "user1" to the qbittorrentvpn docker... same result, no transfer.
Then I did an odd thing... I changed sonarr's PGID to the administrator (leaving its' PUID as "user1")... and success... downloaded files transferred to /media/tv shows/*
When I checked the ownership of the transferred file, it said "admin1". Huh? So both qbittorrentvpn and sonarr dockers used PUID for "user1", but the file ended up with "admin1" as the owner. That seems illogical to me, but I am no Linux master.
The only variable I've yet to try is qbittorrentvpn docker allows for UMASK to be set (another variable I have no understanding of), so I will tinker some more.
But back to @Shadow
's situation... changing sonarr's PGID to that for administrators allowed the transfer to my newly created shared folder (I have no idea whether the system-created folder "video" had any peculiarities that prevent the sonarr transfers... Just a thought (or a ramble).
All that said this seems somewhat academic as there are no new tv episodes to look forward to in our current times, and my sonarr calendar is devoid of future downloads.