[all variants] Bluetooth headset pairs and coects to laptop but no audio

Laptop ruing Xubuntu 16.04 64-bit.

My bluetooth headset pairs and coects to my computer, but I don't get any audio through the headset. The headset is Bluetooth 3.0 with these compatible profiles:
A2DP (Advanced Audio Distribution Profile)
AVRCP (Audio Video Remote Control Profile)
HFP (Hands-free Profile)
HSP (Headset Profile)

I tried coecting the headset as Audio Sink and as Headset. In both cases, the headset is listed in the Output Devices tab of Volume Control (pavucontrol), but caot switch the audio to it. Clicking the check box 'set as fallback' shows the box is checked and redirects the volume control buttons on the laptop to control the headset's volume (can see this in Volume Control, and the volume control buttons no longer control the laptop speaker volume), but does nothing to redirect audio from laptop speakers to headset.

Any suggestions on how to diagnose this?