Maybe I need to post in new thread , but I have similar problem, where my asd keys work intermittently. With no obvious correlation to temperature, battery/power plug, pressure, repetition, other keys...
I have tried mac help & they suggested "sticky keys" which was not the solution.
I tried adding another "input source" through keyboard settings in system, which was not the solution.
I can plug in a usb keyboard & it works fine.
It acts like a software issue in how it is intermittent: on & fine, off & nothing, or off unless I type it 5 or 10 times.