Radarr lxc "Unable to add root folder"

[brachiosaurus19]

Hello, I'm having some trouble adding a root folder to my Radarr lxc instance.
Currently, I have a truenas instance running in its own VM with an NFS share called 'media'. In my proxmox host, I mounted the NFS share as 'truenas-media' and created a group 'media-group'. I gave 'media-group' (with gid 1200) access to the share via truenas. In the proxmox host, I added 'root' as a member of 'media-group' and I am able to access the NFS share properly via the proxmox shell.
I created a Radarr lxc using the community scripts and followed these steps to mount the NFS share from my proxmox host to the Radarr lxc:

1. inside the lxc, I created a group 'media-group' (with gid 1200), and added root to this group
   usermod -aG media-group root
2. on proxmox host, added a mountpoint and idmap for 'media-group' to the config file /etc/pve/lxc/[lxc_id].conf
   

   mp0: /mnt/truenas-media,mp=/mnt/media,backup=0
   lxc.idmap: u 0 100000 65536
   lxc.idmap: g 0 100000 1200
   lxc.idmap: g 1200 1200 1
   lxc.idmap: g 1201 101201 64335

3. in lxc console, changed the group of the newly created /mnt/media to 'media-group'
   chgrp -R /mnt/media-group

Now, I am able to read,write,execute the contents of the NFS share from the lxc console, but when I try to add a root folder via the Radarr web gui, I get the following error message:
Unable to add root folder

• Folder '/mnt/media/' is not writable by user 'root'

Happy to provide any more info if needed! Thanks!