I made a separate thread (After first use keyboard & mouse no longer works, how to recover?) because I didn’t notice that this one exists. Sorry.
What I noticed is that sometimes a quick power supply demand rise (connecting something to usb, which consumes power) can make the keyboard stop.
In such cases turning off and on helps for me currently.
This looks like the kezboard firmware crashing indeed
(also as I reprogrammed the keyboard with the ‘improved trackball firmware’ I think I’m getting this much less often but not sure if this is related at all)
Wouldn’t some kind of watchdog (& restart) in the keyboard firmware solve this?