thx for reply.

Well, SLES12 is running in Hyper-V environment. One problem I have detected: the Hyper-V manager still showing, that an update is needed of the integration services. In the properties of the VM running Suse, all integration services (e.g. timesource, guest, ...) are enabled. Maybe I have to update it with a newer version of these services. But I don't know how and where to get the latest version of it.