I think the cause of this is the positioning of the model in slew mode. Some models do not seem to move whereas others will "jump" off the ground. I ended up by using trial and error until I got a got config (defeats the purpose of the graphical interface)
That's a problem with some models and their contact points. It seems none of them reacts the same way. We already do a correction based on the static_cg_height, but it seems that FSX itself behaves in an erratic way, even with the same airplane.
Aerosoft have found a way round it in AES. What you see in their graphical editor is what you get. It works right away. GSX on the other hand requires trial and error
I hope FSDT finds a similar fix.
This is the FIRST release of the graphical editor, we'll obviously fix this, as we fixed every problem that is being reported right now. It only took a bit more than a week to do the graphical editor from scratch, FSX is not a 5 years-old product, it was released only about 6 months ago...