If this fixes the problem for you perhaps this bug should be updated to point to the PCM one so users can report that it has affected them and ensure the correct priority is assigned.
Please do update the thread to confirm whether this works for you, or the bug report may be closed while an issue remains!
Have you seen this existing bug? https:/ /bugs.launchpad .net/ubuntu/ +source/ pulseaudio/ +bug/272321
If you're unable to set the PCM volume at all, see related bug https:/ /bugs.launchpad .net/ubuntu/ +source/ pulseaudio/ +bug/315971
If this fixes the problem for you perhaps this bug should be updated to point to the PCM one so users can report that it has affected them and ensure the correct priority is assigned.
Please do update the thread to confirm whether this works for you, or the bug report may be closed while an issue remains!