Getting Bluetooth on Ubuntu to work can be challenging. Below is a guideline on how you might accomplish that.
1. Install Blueman
sudo apt-get install blueman
Setup connect to your Bluetooth headset
2. Ensure Gnome doesn’t capture the A2DP sink upon session start
sudo nano /var/lib/gdm3/.config/pulse/client.conf
Add the following lines of code:
autospawn = no daemon-binary = /bin/true
Change the ownership of the file
chown gdm:gdm /var/lib/gdm3/.config/pulse/client.conf
The only caveat here is each time you use A2DP you're going to have to select the A2DP sink audio profile under audio profiles in blueman.