Unable to save resume file: Invalid argument

[AMeynen]

I recently set up a docker on my Raspberry Pi 4. Configuration went smooth thanks to the documentation.
Everything works well except for some torrents, which cannot start. These torrents give the error: "Unable to save resume file: Invalid argument". I cannot specify why some torrents have this issue, whilst most do not. All torrents come from an identical private tracker.

Config:
docker run -it --cap-add=NET_ADMIN
--restart unless-stopped
-v '/media/pi/External/Raspi_Torrents/':/data
-p 9091:9091
-e LOCAL_NETWORK=192.168.0.0/16
-e OPENVPN_PROVIDER=PIA
-e OPENVPN_CONFIG=france
-e OPENVPN_USERNAME=XXXXXXX
-e OPENVPN_PASSWORD=XXXXXXX
-e DISABLE_PORT_UPDATER=true
haugene/transmission-openvpn

Hope someone with more experience can help to resolve this issue!
EDIT: Turns out to be a newbie problem. This problem was due to the format of my storage drive and has nothing to do with the transmission or openvpn.