I run into this problem on nearly every flight since at least the 1.18.15.0 release. I typically hand over ATC chat duties to the first officer on taxi and things typically keep working through departure. Things progress fairly normally through the first handful of frequency changes. But, then starts happening right after a very odd, botched hand-off; meaning that either a). some (new) unexpected voice gets involved in the ATC chatter (usually not involving my aircraft) or b). it’s as if my co-pilot suddenly takes on the role of the ATC center (i.e., their voice is used when providing some instruction). From that point on, the first officer simply replies to instructions that I never hear or see. So it seems something gets thrown off in the expected order of the banter/voices and then ATC goes dark from then on. Though I have to admit that it does add an element of suspense to the flight. Curious if anyone else has had this same experience where some unusual chatter takes place right before the problem occurs.
fwiw: Since I’ve been pretty much flying the CRj everywhere recently (at least for ~1hr flights) I can only speak for experiencing the problem when flying this aircraft.