Update on this: Today I figured out, that this 2h was reported from my side to Avast support on feburary 28th. In this case the 2h also have effect on antivirus report and antivirus detections...
Where the Antivirus report says the detection occured at 8.39 the hub GUI of the related client says it was detected at 10.39.
It is obvious that both problems have the same cause...