segfault in ipengine on linux with windows controller

I'm running controller and the client on a windows host. I start an engine on a linux machine (using `ipengine --file=ipcontroller-engine.json`) and the engine connects fine. If I then start processing in qtconsole under windows and do the following:
```python
import ipyparallel as ipp
c=ipp.Client()
dview=c[:]
with dview.sync_imports():
import numpy
```
The engine shuts down with a segfault: ` “ipengine --file=ipcontroller-en…” terminated by signal SIGSEGV (Address boundary error)` This seems to be independent of the imported module.

ipyparallel is version 6.0.2 on both systems installed via pip under linux and using conda in windows. Both systems are running python3.