SnapRaid Drive dropdown shows nothing

There was another recent post about this, but it didn't help me. I have the following partitions:

# SnapRAID data
/dev/disk/by-id/ata-ST2000DM008-2FR102_ZK200SHY-part1    /mnt/data/disk1    ext4  defaults 0 0  # /dev/sdb1
/dev/disk/by-id/ata-ST2000DM008-2FR102_ZK200S0C-part1    /mnt/data/disk2    ext4  defaults 0 0  # /dev/sdd1
# SnapRAID parity
/dev/disk/by-id/ata-ST2000VN004-2E4164_Z52317GF-part1    /mnt/parity/1-parity  ext4  defaults 0 0  # /dev/sdc1

They are all mounted, and appear as mounted, online, and not referenced under Storage >> File Systems.

When I open the SnapRAID tool and try to select drives, it appears to briefly search for drives but nothing shows up in the dropdown.

Oh, OK. Yeah I'd done the partitioning and mounting outside of OMV before installing OMV. I can see why OMV would need to manage that for SnapRAID to find the disks. Thanks.