On Ubuntu 20.04 the problem is still happening pretty similar to the one reported by the OP. I've found a new way to fix it though.
Steps to reproduce: 1. turn off machine. 2. leave a headphone plugged in 3. turn on machine (caveat: if your laptop is suspended from here the bug won't be produced) 4. unplug headphone 5. plug headphone -> YOU WON'T HEAR A THING To fix it I do: I open Settings -> Sound and there: 1. Change the Output Device to the normal speakers 2. change the Input Device to internal microphone (not the headphone) 3. Change the Output Device to the headphone 4. Change the Input Device to the headphone (this fix is faster than suspending and bringing it back up). Another fix, is to always unplug the headphones when turning off the laptop. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1575078 Title: [XPS 15 9550, Realtek ALC3266] Headphone jack stops working after a while To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/alsa-driver/+bug/1575078/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs