bluetooth audio and microphone issues

[gcr]

I generally use my laptop with zoom. Have started to have problems with bluetooth headset(s), one is Sony WI-C400, the other is Sennheiser HD200. During the pre microphone/speaker test, I get the tones and microphone sensing. As soon as the actual acceptance from the host, everything is dead. Have toggled through the various headset options on the zoom window as well as W10 systems 'sound' page. 

This hasn't always been a problem, quite regularly had used the Sony unit. Problem has become apparent about 3 months ago. Have unpaired/repaired the units without success. The only thing I haven't done is uninstall/re-install zoom. Headsets work fine on Signal and WhatsApp.

I see some comments re possible conflict with android phone mic, but if not using the phone not sure why there could be a problem. Haven't tried turning phone bluetooth off.

Any suggestions?

gcr