I encountered the same problem yesterday. After manual startup following the full checklist procedures as I normally do
during engine startup
starting engine 2 and resetting gen 2
disconnecting ground power after gen 2 gave power
starting engine 1 and resetting gen 1
I then wanted to proceed but everything stopped working but strangely the engines kept running. So it looked like a system failure or a picnic (problem in chair not in computer). I was not in the mood to investigate, so started the eclipse and made the flight with that plane.
What was different this time that I can remember:
I upgraded the nvidia drivers, used the avitab early in the flight planning even before engine startup and I also had to make some configuration changes to Pilot2Atc because with the Saab there are some com things that behave different than with the other planes
If i’m I’m the mood for some debugging this week I‘ll post my findings