Left Shift/Control/Option keys don't work Yesterday the shift stopped working most of the time (it works 1/100) suddenly (did not spill anything), and the weird thing is that today the Control &amp; Option keys joined the party — they stopped working (only left keys).

It's a MacBook Pro "Core i7" 2.2 15" Mid-2015 (IG) (MJLQ2LL/A).

I have tried the keys in my Windows VMWare and they don't work. In keyboard viewer in Mac they are not highlighted when tapped.

How to know for sure if this is a hardware issue (with keyboard or elsewhere too) and how can I fix the problem?

Update: External bluetooth works fine
Try resetting the NVRAM on your Mac using this guide - https://support.apple.com/en-ca/HT204063

If those keys do not work even after the NVRAM reset, then you will have to consult with a repair shop or go to the Apple Store and ask to get your keyboard fixed or replaced.