Problems re-attaching SATA drive to Ubuntu 20.04 VM

[cfcman]

I needed to replace a faulty drive in my Ubuntu 20.04 VM (on Proxmox VW 8.25). After a reboot, 3 of the disk drives which were previously attached to the VM had become detached. I needed to re-attach them using the qm set command. This worked fine for 2 of the 3 missing drives, but I am unable to mount the 3rd drive (from the Disks UI). I get this error when I try to mount it:

"Error mounting filesystem. Error mounting system-managed device /dev/vdc: wrong fs type, bad option, bad superblock on /dev/vdc, missing codepage or helper progam, or other error (udisks-error-quark, o)"

If I try to "Repair Filesystem" I get:

Error while repairing filesystem. Not authorised to perform operation (udisks-error-quark, 3)

I get the same error if I try to format the partition.

Any idea how I can fix this?