Ralf,
Qtree SnapMirror is not supported in Snap Creator.
Traditionally it has worked, but it has never been a supported configuration.
Lots of changes to this code were needed for clustered Data ONTAP 8.2 support in Snap Creator 4.1.
Apparently one of these changes broke QSM.
Since it wasn't supported it wasn't in our group of test cases and we were not aware that it broke until after the 4.1 release.
Engineering and Product Management are evaluating the options at this time.
Sorry for the inconvenience.
John