GFS Backup job with replication - replication fails: "URI is empty"

Hi Team!

Since a few days my backup Job (SBS Server to NAS01 replicated to NAS02) fails with the following MSG:

ProtectCommand: Ausführen des Befehls fehlgeschlagen.
Zusätzliche Info:
--------------------
Fehlercode: 41
Module: 307
LineInfo: e6792a5ee190dd9e
Felder: $module : agent_protection_addon_vs
Nachricht: ProtectCommand: Ausführen des Befehls fehlgeschlagen.
--------------------
Fehlercode: 1
Module: 38
LineInfo: ea40b4277fbfb9d2
Felder: IsReturnCode : 1, $module : disk_bundle_vs
Nachricht: URI ist leer.
--------------------
Fehlercode: 1
Module: 38
LineInfo: ea40b4277fbfb9d2
Felder: $module : disk_bundle_vs
Nachricht: URI ist leer.
--------------------
I use Backup&Recovery 11 Advanced for SBS + UR. I even updated to the latest build 11.0.17440.
Can anyone advise? I did the following:
- reboot Acronis Services
- reboot both NAS devices
- update Acronis Software

Thanks for any tip.