Just bought an ASUS C434 Flip Chromebook to test using Chromebooks for work and have the same issue.
I’m using NoMachine Android 6.1.9 and this is a new Chromebook that upgraded to Chrome OS 80.0.3987.137
Everything in terms of setup seems to work but when I try to connect (to Ubuntu EC2 via VPN), I get the same.
It freezes on “Connecting to <session-name>” and then eventually I get the “this application is unresponsive – wait, close, or report.
I’ve signed up for email notification on the TR and would be more than happy to try the APK and load that in developer mode.