I've got lots of issues with Transmission recently. I can't figure out how to fix this.
I'm trying to download torrent directly to my external HDD instead of the dietpi_userdata folder. Downloading a torrent to the micro SD works, but not on the external HDD. The HDD is ext4 formatted and mounted in /mnt.
When I try to download a torrent to this location, the download works for a few minutes then it just stops. I can't relaunch it.

I have the error "permission denied". I don't understand why, I'm logged in with root user, as mentionned in the dietpi docs, and it even worked for some minutes. I tried reinstalling transmission, didn't work. The issue is still there.
I searched a lot on the issue, didn't find anything on it.
Any help is welcome
Have a good day