HP Spectre x360 - 13-4172na no audio

[ColonialCascade]

I have no audio or microphone input from my 2 in 1 spectre.  Even adding earphones is no help.  No audio comes through.

I have downloaded and used the HP support software several times and gone through all of the steps.

'no audio device is installed' when speaker icon is hovered over.

The PC is a factory reset ex. PC World display.  It comes with windows 11, but will not update to 2H22.  This leads me to believe it was originally shipped with Windows 10.

I have done all the diagnostics tools.  No hardware faults found via the HP support assistant.

However, the HP audio check says no speakers or microphone found (hardware issue). 

I have removed/reinstalled realtek drivers, and, as another answer suggested the issue was B&O related I downloaded the B&O app (which will not open and says 'cannot connect to RPC', which suggests a realtek driver issue), so that was no help and may be a red herring for me.

When checking the BIOS (updated) the version is SMBIOS 2.8, american Megatrends 1/7/2019 F53

I have autoupdated the BIOS, but all recent posts suggest BIOS 6 or 7?  Is this machine really old?  It seems new.

when checking the system info it says Multimedia Audio Controller, the drivers for this device are not installed.

I go to the HP website to download drivers and do the download, for my PC it only gives me Windows 10 Driver options, than says up to date drivers are installed.

Frustrated.  Both cannot be the case.

I thought it was because the B&O App was missing and I had to initialise, I thought it was a hardware issue, I thought it was a driver issue and now I have no idea what to do.

I would like to get the sound and microphone working please.  

I believe I need to install a suitable driver and then adjust the B&O settings ??  I could be wrong!!!

Are there Win11 drivers for this setup ?  Do I need to reset to Windows 10? (I'd rather not, and how do I?)

Why cant I bypass the B&O App setting if I go straight through the BIOS to try and get some audio?

Help/suggestions appreciated.