SAP Sync Problems - Process task FullSync Failed

Hello,

we are running Quest One Identity Manager in version 6.1.3 in our productive environment.
Due to several errors with SAP, we checked the logs for errors and found that the following message appears there.


(...)
    Start processing object class /  relation of type "SAPGROUPAgr_Name" using following settings: 
    Database amount : MARK, 
    Intersection amount: UPDATEDB,
    Namespace amount: IMPORT - USN optimization False.
    Start processing object class /  relation of type "SAPPROFILEPROFN" using following settings: 
    Database amount : MARK, 
    Intersection amount: UPDATEDB,
    Namespace amount: IMPORT - USN optimization False.
    Start processing object class /  relation of type "SAPROLEPROFILE" using following settings: 
    Database amount : MARK, 
    Intersection amount: UPDATEDB,
    Namespace amount: IMPORT - USN optimization False.
    Start processing object class /  relation of type "USER" using following settings: 
    Database amount : MARK, 
    Intersection amount: UPDATEDB,
    Namespace amount: IMPORT - USN optimization False.
Process task FullSync failed.
(..)

However, the job chain "VI_SAP_SAPMandant_Fullsync" runs through without error, which is why we have probably not noticed. On the SAP side, there are no errors or warnings in the log at the time of sync.
An internet research has not yielded much evidence for solving this problem.
Why does FullSync fail with SAP? What else can we test to get closer to the cause?

Thanks for any hints.

Kind regards