If GUI config tools are failing to set and activate bluetooth headset on linux try:
pacmd set-card-profile `pacmd list-cards | grep bluez_card -B1 | grep index | awk '{print $2}'` a2dp_sink
source https://ubuntuforums.org/showthread.php?t=2338355
edit: nope still fucked...
https://gist.github.com/pylover/d68be364adac5f946887b85e6ed6e7ae#file-a2dp-py
edit 2:
this one seems to work for now:
https://bugs.launchpad.net/ubuntu/+source/bluez/+bug/1438510/comments/5
edit 3:
pactl load-module module-bluetooth-discover