Hi Dave:
I found I bug that I can reproduce. When asking ground for a different runway than the one assigned, everything is fine at first and the new runway is approved and taxi directions given. However, a minute later I get a strange transmission (cleared to <blank>, altimeter is <blank>) and then there are no more communication with any facility for the rest of the flight. PF3 is still running and I can even get ACARS but no coms. Similar behavior also happens on approach if a different runway is requested, the strange second clearance happens, but in that case communications continued.
Also, I think the algorithm for detecting the proximity of the aircraft to parallel runways is off a bit. I can be parked right next to a runway, but get cleared to a parallel runway on the other side of the airport. In this case I was at KMIA parked at the H gates which is close to RWY 17 but received clearance to 16L which you'd have to call an Uber to get to it's so far away LOL!
Debugs attached.