My headphones connect and disconnect immediately. Blueman shows br-connection-canceled
When I tried different combinations of turning Bluetooth on and off, my headphones connected but weren't detected as output device.
EDIT: I have some progress! So I tried to connect using terminal
bluetoothstl scan on
bluetoothstl connect XX:XX:XX:XX:XX:XX
(here goes mac address of your device)
And it worked just fine!