[APP] Transmission various versions for firmware V4+ (05/2020)

Not sure why your new files are created as permission 644, it’s showing as permission 664 for mine so it’s writable to group share.

Try below:
transmission-stop;

sed -i 's/"umask": 18,/"umask": 0,/g' ~/.config/transmission-daemon/settings.json>/dev/null 2>&1;

transmission-daemon;

If it still doesn’t work, I don’t know what changes that has been brought to OS3. If that’s the case then you will need to first “Copy & Paste” the downloads to your preferred destination via SMB shares, then remove the torrent including its data from the WebUI. Another way is to script your own post-processing script to modify the permissions which I’ll not elaborate further here.