@dietmar i also faced the exact same problem. The only differences is that i could mount the drive
root@local:~# pveversion -v
proxmox-ve: 5.1-42 (running kernel: 4.4.114-1-pve)
pve-manager: 5.1-46 (running version: 5.1-46/ae8241d4)
pve-kernel-4.13: 5.1-43
pve-kernel-4.13.16-1-pve: 4.13.16-45...
