Bluetooth headset microphone not used

Dear community,

it seems that on both my devices (Xperia XA2 - main phone, and AquaFish=JollaC) the microphone of bluetooth headsets i have and tried is not used.
At the beginning i thought the mic volume is too low but i realized that only the internal mic is used for recording even if BT headset is connected.
I checked with pactl and the BT source device is there.

The same BT headsets work fine with other android phones.

Does anyone have the same issue? What else could i tinker with so that i solve my issue?

P.S. as i was writing this post i realized that i use regularly the BT connection of my car audio to make phone calls … i believe there it is not the internal phone mic which is used
Is there a way to select the mic for recording?

Regards
binu

Audio Output Chooser from Openrepos is worth a try, although it takes some time to understand all the options.