I've solved this exact issue and numerous others with samba / CIFS recently. This is how I have my Proxmox on a mini pc with usb mounted HDDs at present:
1 VM Home Assistant OS, not relevant really
1 VM OMV Open Media Vault.
1 VM Debian with Docker installed.
So in my experience over the last few months you want your usb drive to have absolutely nothing to do with Proxmox. Nope.
I had 3 hooked in mounted in Proxmox and when one of them threw a fit Proxmox refused to load.
Better to have a NAS VM installed and have the drive(s, I have 3, 2x1tb and 1x750gb) passed straight through, whole usb, to the NAS VM.
This means if the drive fails Proxmox doesn't break, and also in my experience with OMV, it'll still run if a drive breaks
Then what I did was set up the shares and made them samba in OMV then set my other VM, the Debian one, with mount points in the Fstab.
The key for me in this endeavour was to make sure the Fstab entry made sure that the OS wouldn't fail if it couldn't find a drive, as happened in Proxmox, so I made sure "nofail" was somewhere in the Fstab config.
For Samba to work in Linux you need to install cifs-utils, then add a line in /etc/fstab. Mine goes:
Then what I do for Audiobookshelf and whatnot is mount the mount point as directories in Portainer under the volumes:
- /mnt/Downloads:/Downloads
Then in the UI of the service I'm using in Docker I can use the Downloads folder and it's the mount point.
This is what's working well for me. If a drive fails I try and fix it in OMV instead of trying to plug a monitor into my mini pc to try and work out from the logs why Proxmox has failed...
Use this comment as a framework for your research and save yourself some heartache. You can mount the CIFS/Samba share to Proxmox and use that, so you can still use the drive in Proxmox for backups and such