When I have my headphones plugged in sometimes I don’t get sound from my right headphone. I’ve tried several pairs of headphones, so it’s not the headphones. With the same laptop on Windows 10 I have no issues, so it’s not the jack itself. If I unplug my headphones I get sound from both speakers. I’ve tried running alsamixer to see if it’s the balance, but it’s set properly. The odd part is a few reboots will resolve the issue until I reboot again and run into the same issue.
If it’s not the hardware (headphones or soundcard output plug) then it could be the driver. However to be absolutely sure it would be nice to have some data on when the actual problem occurs.
So when the problem occurs try looking at alsamixer and maybe also save the current dmesg messages that might indicate what the problem could be.