Makes sense to me Roamer - the controller settings change when using the goggles (the custom buttons change to a preset forced by the goggles) which is part of what makes me believe you are spot on - the goggles take over somewhat...Not sure that this is the real reason. Based on my tests and observed behavior it seems more like a fundamental control protocol issue. For example, if there are no goggles and all is set to Automatic the GO 4 app is in charge to manage channel and frequency changes communicating to the M2 via RC to switch. The M2 behaves in a subordinate mode. When you add the Goggles, there is a separate connection between the M2 and the goggles. The firmware in the goggles essentially behaves much like the GO 4 app in the it wants to communicate to the M2 to switch channel/frequency if needed. The two simply collide and neither will end up knowing what the frequency should be - hence complete and abrupt loss of connection. DJI has to change/add handshake options to force the goggles to take a subordinate role when an RC is connected as well.
So if I force the frequency/channel to a fixed setting after initial RC connection to the M2 BEFORE turning on the goggles and the start the goggles, the goggles appear to be “told” during the M2 handshake that the coms are fixed (M2 can’t change) and everything works great. I flew well over 2 miles from home point without any problems.
So, once the “B engineering team” (goggle team) figures that out and coordinates this substantial (but not very difficult to solve) change to the ongoing handshake protocol some future firmware change affecting all components will make this all work great. Meanwhile follow my approach - I hope it will work for you too.
I too have the RE - good for zipping around close by - but standing in the same spot on the same flight (chasing my sis in law car home) i got out to 500m - and was choppy and almost disconnecting - told my son to turn off the goggles - bang instant solid connection - flew to 2.5km away before it got choppy again (metro area) - all in the same flight.
Looking forward to them sorting it.