Precision 7770 / OpenSUSE 15.5 / Microphone not working

I have a fairly new (built in March) Precision 7770 with a fully-patched OpenSUSE 15.5 installed.

On the whole, it is working fine - except for the microphone (but the speakers work) - I would appreciate assistance troubleshooting this

I have been following the OpenSUSE sound troubleshooting guides without much success:

https://en.opensuse.org/SDB:Audio_troubleshooting

https://en.opensuse.org/SDB:Pulseaudio

https://en.opensuse.org/SDB:Intel-HDA_sound_problems

I have run the ALSA-Info script - here's a subset of the output:

!!Kernel Information
!!------------------

Kernel release:    5.14.21-150500.55.31-default
Operating System:  GNU/Linux
Architecture:      x86_64
Processor:         x86_64
SMP Enabled:       Yes


!!ALSA Version
!!------------

Driver version:     k5.14.21-150500.55.31-default
Library version:     
Utilities version:  1.2.8

!!Loaded ALSA modules
!!-------------------

snd_hda_intel (card 1)

!!Sound Servers on this system
!!----------------------------

PipeWire:
     Installed - Yes (/usr/bin/pipewire)
     Running - Yes

Pulseaudio:
     Installed - Yes (/usr/bin/pulseaudio)
     Running - Yes


!!Soundcards recognised by ALSA
!!-----------------------------

1 [HDMI           ]: HDA-Intel - HDA Intel PCH
                     HDA Intel PCH at 0x604f240000 irq 211


!!PCI Soundcards installed in the system
!!--------------------------------------

0000:00:1f.3 Audio device [0403]: Intel Corporation Alder Lake-S HD Audio Controller [8086:7ad0] (rev 11) (prog-if 80)
       Subsystem: Dell Device [1028:0b2b]


!!Modprobe options (Sound related)
!!--------------------------------

snd_hda_intel: model=dell-e7x id=HDMI enable=1 index=1