[PyQt] Undefined error with Drag & Drop

[hjm]

I'm runinng into a crash while doing Drag & Drop in QTreeView. If I drop 
over a root item I get the following messages:

failed to initialize logger
ZMQ_EVENT_CONNECT_DELAYED
ZMQ_EVENT_CONNECTED
ZMQ_EVENT_CONNECT_DELAYED
ZMQ_EVENT_CONNECTED
ZMQ_EVENT_CONNECT_DELAYED
ZMQ_EVENT_CONNECTED

If I drop on same level or below, it works.

System Windows 7, python 3.6, pyqt 5.9, development with pyCharm 2017.3.

Can someone explain the messages or behavior. I have actually no idea 
where to search.

Thanks, Hans