Volume keys/OSD detached from pulse after some situations with multiple sinks

[byteit101]

Expected behavior

Pressing X86AudioMute, X86AudioRaiseVolume, and X86AudioLowerVolume should change the volume of the default sink in pulse audio, and show the current volume via the OSD

Actual behavior

Pressing X86AudioMute, X86AudioRaiseVolume, and X86AudioLowerVolume show a volume via the OSD, but it isn't necessarily tied to the default, or even real. In some cases the volume is a secondary sink, and in other cases it's nothing at all.

Steps to reproduce the behavior

This is a bit fuzzy, but it seems to be triggered by some unknown action after I have added multiple sinks, such as a new hardware device, and a combined sink, and then it changes to the non-default sink. If pulseaudio crashes/is killed, then it sometimes becomes detached from any real devices and I have to kill mate-settings-daemon to restore working order.

If it is merely on the wrong device, I must remove/add that device and the real device in this order to restore the correct default:

1. remove correct sink
2. remove current attached sink
3. add current attacked sink
4. add correct sink

MATE general version

1.20.4

Package version

1.20.4-1

Linux Distribution

Debian 10

[thican]

I also confirm I have this issue for a while, even with MATE Media version 1.24.1. I thought it was related to PipeWire, but it behaves as PulseAudio, as declared from pactl info

Server String: /tmp/.runtime-1000/pulse/native
Library Protocol Version: 33
Server Protocol Version: 35
Is Local: yes
Client Index: 73
Tile Size: 65472
User Name: *discarded*
Host Name: *discarded*
Server Name: PulseAudio (on PipeWire 0.3.30)
Server Version: 14.0.0
Default Sample Specification: float32le 2ch 48000Hz
Default Channel Map: front-left,front-right
Default Sink: alsa_output.pci-0000_0a_00.4.analog-stereo
Default Source: alsa_output.pci-0000_0a_00.4.analog-stereo.monitor
Cookie: d3b4:4427

EDIT: I forgot to mention some information:
MATE general version
1.24.1
Package version
1.24.1
Linux Distribution
Gentoo

[NinjaCowboy]

I'm having the same issue after switching from Pulseaudio to Pipewire. The volume control slider applet (mate-volume-control) in the panel works fine no matter which profile I select, but the volume keys only work for the analog ones, not HDMI. You can see here how when I press the keys, the OSD always shows up, but the volume only changes (seen in the "Output volume" slider) when I have the analog output selected.
Video demonstration here
I suspect that mate-volume-control and whatever handles the shortcut keys are looking in different places to determine which audio device to control. mate-volume-control gets the correct one, but the shortcut key handler gets the wrong one.