Apple Watch Series 3/Bose Sound Sport - Answering calls

I can receive calls on my watch perfectly but when I answer them they do not come through to my bluetooth device and when I try and set the device using the icon below the call it ignores it. Just won't go over to the device. Incredibly frustrating if you're in a noisy environment and you're trying to listen to your wrist like some sort of dope. Devices are all paired and when the phone call is finished the Bose bluetooth resumes playing music without issue.