sybok
It seems that two users are involved, namely ‘debian-transmission’ and ‘aledosin’.
0) Could you post details about the running process?
Is it running with the correct user and hence permissions?
It could be output of ‘ps -ef | grep transmission’
1) How did you set the permissions?
I usually run ‘sudo chown <new owner> -R <path to> && sudo chgrp <new owner> -R <path to>’ but that applies to different use-cases|circumstances.
2) Is the former user in the group of the latter or there is no such connection?
Explore ‘/etc/group’, e.g. grep the users.
Adding the transmission user to your user group might simplify certain permission things but it could made your data available to the transmission user.