Can't change audio device on Linux, only option is "System Default" and sound always goes through HDMI

Describe the bug
The only audio device that I can select is "System Default" and I can't get MuseScore to output sound to anything else besides my HDMI monitor. I have tried my audio jack and a bluetooth headset, but MuseScore insists on using HDMI. It sends sound through HDMI even if the HDMI device is muted in Audio Settings, and even if I have my entire system muted! Even more strangely, if I disable the HDMI device it still sends sound through it, despite another audio sink being the only one available (see screenshots). Because of this strange behavior, I have been unable to use MuseScore with any headsets.

(Also, relaunching MuseScore or pulseaudio both do not help.)

To Reproduce
Steps to reproduce the behavior:

1. Set systemwide audio output device to something other than HDMI
2. Open MuseScore
3. Play something
4. Sound goes through HDMI still
5. Mute HDMI and try again
6. Sound goes through HDMI still
7. Disable HDMI device and try again
8. Sound goes through HDMI still
9. Cry

Expected behavior
Sound goes through whatever is the system default, and/or MuseScore allows you to choose which audio device to use.

Screenshots
msc-broken-audio-scrots.zip
(Sorry, my browser is being weird and I can't upload individual images)

Platform information

                   -`                    [redacted] 
                  .o+`                   ----------- 
                 `ooo/                   OS: Arch Linux ARM aarch64 
                `+oooo:                  Host: Raspberry Pi 4 Model B 
               `+oooooo:                 Kernel: 5.19.8-1-aarch64-ARCH 
               -+oooooo+:                Uptime: 23 hours, 18 mins 
             `/:-:++oooo+:               Packages: 1021 (pacman) 
            `/++++/+++++++:              Shell: bash 5.1.16 
           `/++++++++++++++:             Resolution: 1920x1080 
          `/+++ooooooooooooo/`           DE: Plasma 5.26.5 
         ./ooosssso++osssssso+`          WM: KWin 
        .oossssso-````/ossssss+`         Theme: [Plasma], Breeze [GTK2/3] 
       -osssssso.      :ssssssso.        Icons: [Plasma], breeze-dark [GTK2/3] 
      :osssssss/        osssso+++.       Terminal: konsole 
     /ossssssss/        +ssssooo/-       CPU: (4) @ 2.000GHz 
   `/ossssso+/:-        -:/+osssso+-     Memory: 1303MiB / 7797MiB 
  `+sso+:-`                 `.-/+oso:
 `++:.                           `-/+/                           
 .`                                 `/                           

Additional context
As shown in one of the screenshots, the dropdown at Edit > Preferences > I/O > Audio > Audio Device has only one option, system default. Contrary to this, MuseScore does not appear to respect the system default.

The issue identifies Edit > Preferences > I/O > Audio > Audio Device and provides Linux reproduction steps, but no source files or tests. First reproduce the HDMI routing and inspect the audio-device preference and Linux audio integration; done means MuseScore lists available devices and sends sound to the selected device or system default.