Docking station audio output not retained on swapover

[Casio]

Ubuntu 22.04 on a Dell M6700 laptop, normally connected to a docking station.
Default configuration is audio output via the Docking station audio output connector.

Listen to a radio station to prove audio comes out of the docking station audio output.
Power off Ubuntu via the top right menu.

Remove laptop, plug in somewhere else standalone, power up laptop, use it, then power it down again.

Plug laptop back onto docking station, power up, audio now only comes out of the Dell M6700 audio output.
There is no other audio output option listed in the Settings... Audio page.

Rebooted several times, removed\connected docking station; tried restarting alsa, PulseAudio service - no effect, still don't get any alternative audio output listed in the settings audio page.

[Ubuntu Foundations Team Bug Bot (crichton)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. It seems that your bug report is not filed about a specific source package though, rather it is just filed against Ubuntu in general. It is important that bug reports be filed about source packages so that people interested in the package can find the bugs about it. You can find some hints about determining what package your bug might be about at https://wiki.ubuntu.com/Bugs/FindRightPackage. You might also ask for help in the #ubuntu-bugs irc channel on Libera.chat.

To change the source package that this bug is filed about visit https://bugs.launchpad.net/ubuntu/+bug/2067269/+editstatus and add the package name in the text box next to the word Package.

[This is an automated message. I apologize if it reached you inappropriately; please just reply to this message indicating so.]

[Casio (casiobearing)]

The only output device I get in the sound settings is "Line Out - Built-in Audio" (thats the Dell M6700 internal speakers).
I did a "lshw" and here is some of the listing...
Why is the "HDA Intel PCH Dock Line Out" listed as "/dev/input/event21". shouldn't it be an output?

            description: Audio device
             product: 7 Series/C216 Chipset Family High Definition Audio Controller
             vendor: Intel Corporation
             physical id: 1b
             bus info: pci@0000:00:1b.0
             logical name: card0
             logical name: /dev/snd/controlC0
             logical name: /dev/snd/hwC0D0
             logical name: /dev/snd/pcmC0D0c
             logical name: /dev/snd/pcmC0D0p
             version: 04
             width: 64 bits
             clock: 33MHz
             capabilities: bus_master cap_list
             configuration: driver=snd_hda_intel latency=0
             resources: irq:32 memory:f7e30000-f7e33fff
           *-input:0
                product: HDA Intel PCH Dock Mic
                physical id: 0
                logical name: input20
                logical name: /dev/input/event19
           *-input:1
                product: HDA Intel PCH Mic
                physical id: 1
                logical name: input21
                logical name: /dev/input/event20
           *-input:2
                product: HDA Intel PCH Dock Line Out
                physical id: 2
                logical name: input22
                logical name: /dev/input/event21
           *-input:3
                product: HDA Intel PCH Headphone
                physical id: 3
                logical name: input23
                logical name: /dev/input/event22

[Casio (casiobearing)]

Extra info - With the laptop fixed to the docking station, audio coming out of the Dell M6700 laptop is not being muted when external speakers are plugged into the docking station Line Out jack.