Appliance for Raspberry Pi 4:system upgrade from 1.10.4 to 1.10.6 leads to: There was an error. The backup storage is currently not available

Hi there,
today I let my appliance do the system update from 1.10.4 to 1.10.6. After finish the update the appliance restarted and now my cloud drive is lost: There was an error. The backup storage is currently not available. (myappliance)
No attached devices (disks) detected …
Cloud storage
Encryption key:
|Allocated storage (uncompressed):|NaN bytes; NaN bytes used (%)|
|Used storage (encrypted and compressed):|NaN bytes|
I rebooted several time but the situation did not change at all.
Well, I have no idea what to do now. How can I reconnect my cloud drive to my appliance? Please help.