Update:
It did seem to resolve my problem initially, though now the headphones are not shown as an output device. Regardless whether they are re-paired, manually connected via BT or automatically connect once paired. Following the tutorial instructions, the file to modify does have persistent changes between boots.
Other Bluetooth units work fine. This includes both non-audio units (Logitech MX Ergo mouse) and audio units (Antlion Modmic Wireless).
Really uncertain of how I should continue the troubleshooting process.
Update 2:
After removing cookies from ~/.config/pulse the headphones are automatically added to the list of output devices. Seems to solve the problem, but annoying if this need to be done at regular intervals 