Rainbow ignoring or not recognising Bluetooth headset

I have an issue with Rainbow just not recognising my bluetooth headset (plantronics backbeat Go 2) running on a Samsung Android A5.

It appears Rainbow completely ignores the headset. Every other app on my phone recognises it though. 

I find I can't answer a call, make a call or even listen to a voicemail - instead it plays it to the speaker. 

Is there a bug with headset support?