Sound not working on Ubuntu 20 (or 21) on ASUS UX450FDX

Speakers do not work on Ubuntu. My mic works.

When I plug in a headset, the headset speakers work (although it does not recognise the headset mic, I have to go into settings and change the mic to the internal laptop mic).

I have updated my laptop from Ubuntu 20.04 to 20.10 to 21.04, this has not helped any of my audio issues.

My laptop is also dual-booted with Windows 10, and the speakers have stopped working in Windows 10 (this was not always the case).

Output from inxi -SMA:

System:    Host: zenbook Kernel: 5.11.0-18-generic x86_64 bits: 64 Desktop: GNOME 3.38.4 
           Distro: Ubuntu 21.04 (Hirsute Hippo) 
Machine:   Type: Laptop System: ASUSTeK product: ZenBook UX450FDX_UX480FD v: 1.0 
           serial: <superuser required> 
           Mobo: ASUSTeK model: UX450FDX v: 1.0 serial: <superuser required> 
           UEFI: American Megatrends v: UX450FDX.313 date: 01/17/2020 
Audio:     Device-1: Intel Cannon Point-LP High Definition Audio driver: snd_hda_intel 
           Device-2: NVIDIA GP107GL High Definition Audio driver: snd_hda_intel 
           Sound Server: ALSA v: k5.11.0-18-generic 

This is not the first issue I have had with this setup (Ubuntu + Windows on Asus laptop). My wifi+bluetooth never really worked either. I am starting to think this combination of software and hardware is not designed to work together!

Things I have tried (apart from updating the ubuntu OS):

1. Reinstalling pulseaudio and alsa-base

sudo apt remove --purge alsa-base pulseaudio
sudo apt install alsa-base pulseaudio

2. Installing pavucontrol and alsa-mixer

Any help would be greatly appreciated.

Ok.

I fixed this, although I am not entirely sure how. This is what I did:

1. Opened up my BIOS and switched SATA configuration from ACPI to Intel. This broke my boot, so I switched it back.
2. In BIOS I switched the I/O configurations to locked for my HD audio devices and turned off Secure Boot. I booted into Linux and that there was just a Dummy Output in place of the speakers. alsamixer seemed to only recognise the NVidia card, but it had no sound outputs.
3. Rebooted and went into BIOS, unlocked the HD audio devices again. Reboot and in sound settings everything appears to be broken. But when I opened up alsamixer the sound looked to work fine.Opened spotify and the sound worked!

So the only difference from the beginning to the end of that process is SecureBoot is now off. Not sure why this would affect the laptop speakers.

In sound settings there are two options for device output. 1. HDMI/Displayport - Builtin Audio and 2. Speakers - Built-in Audio. The first does not work (I think this is picking up an external monitor as having speakers, which it does not!)

Anyway, selecting 2. makes laptop speakers work! Plugging in a headset makes the sound come from the headset, but the mic is still only set to the laptop mic.