@Mark further information on this. When pressing esc for the sim menu (even briefly) and then resuming flight:
CMPMSTR warning
autopilot panel appears to completely loose power and then comes back on
autopilot disconnect warning (can be silenced with two clicks on disconnect)
autothrottle disengaged with IAS reset to 100knts
to recover I must:
cancel the AP disconnect warning (this causes the MCP to go completely dark for a second and then power on again with IAS at 100)
reset IAS to cruise/climb speed
turn off the FDs and turn back on
-wait approximately 20 seconds (nothing will happen until i wait)
re-enalble autothrust
re-enable AP, Lnave and either LVL CNG or ALT
So I CAN get the airplane back. The symptoms of it are almost akin to someone pulling the fuse on the MCP module forcing it into a reset from power off.
recreation advice
i had continuous ignition armed - this may be why the engines came back as they seem to spool down/shut off - i've had situations where the engines would not restart
ensure APU is OFF
ensure you are in climb phase (climb power / above 10,000)
repeating ESC to menu and resume a number of times to see if you can recreate the bug
I have captured a video below:
video of bug - RJ100 - MSFS2020