Hue Emulation - Device is Unresponsive


I have my main Openahab environment which is currently running on Windows using Cloud Connector for Alexa integration - all fine.

I am setting up a new environment on Ubuntu Server 18.04. This time I want to use Hue Emulation for Alexa integration.

With a few items enabled and Hue Emulation enabled, Alexa can discover the devices, but often shows the device as “Device is unresponsive” and so doesn’t switch them on or off. Sometimes it will work for a few minutes perfectly, other times, unresponsive.

I tried enabling Hue emulation on my Windows instance - and everything works like a charge - no unresponsive errors.

I’ve upgraded the Ubuntu instance to 2.5M1 to test as well - same results. I have tried many things without any improvement.

Anybody got any ideas?