Headphone jack stopped working

Hardware
1

My headphone jack has inexplicably stopped working.

The speakers work fine and the Sound settings dialog recognizes when headphones are inserted or removed but the sound does not come out.

I do hear a brief connect / disconnect arc in the headset as the plug goes in and out but no computer audio.

I have tried different headphones both traditional 3-pin and 4-pin ones with microphones and no sound.

2

I have been living with this problem by plugging my headphones into my external monitor and selecting that output.

I have just tested the headphone jack using a Linux Mint Live USB stick and it works fine. My headphones continue to not work in PureOS after rebooting.