Only one laptop speaker working after wiping W10 & installing Core 18

alsamixer F5 shows All channels, both Playback and Capture. So don't worry about that.

What does F6 show for soundcard/s?

We are seeing a lot of sound issues with Intel Sound Cards, so determining exactly what soundcard you have and investigating from that may help.

I assume all the basic pre-installation checks (e.g. BIOS Secure Boot, Fast Boot disabled etc) have been carried out as described here: Before you install

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