The design uses a CH7317B on the SDVOB pins to drive the VGA connector.
The system needs to work with the standard Windows driver for the chipset not an IEGD et al driver.
If the system boots with a VGA display connected the system works properly not show any signs of "MID" in the Intel Graphics GUI. Unplugging and plugging in different displays etc works as expected. If the system boots with a VGA display not connected the system doesn't start displaying on the VGA port when a display is connected. Using vnc to look at the Intel Graphics GUI after booting with no display connected it seems to be indicating it's expecting but not finding a MID display. Even after plugging in the VGA display the Graphics GUI is still expecting to find a MID display.
Crtl-Alt-F1 does force the VGA display to become active. An looking at the Graphics GUI with VNC when the VGA display is unplugged again the GUI is now not expecting a MID display and plugging and unplugging the VGA display now is handled as expected by Windows.
What are we missing to properly configure the system to that the VGA port "just" works and properly handles booting with no VGA connected ?