Hi Franz
indeed it is, I have a full xp12 install including all the ares and then the true earth scenery is installed on top of this. If i disable the true earth scenery and therefore use the default scenery the heights show correctly as you’d hope.
I did try this morning flying in a area with self made ortho4xp scenery (scale 17 but with mesh data settings at default ie mesh data derived from the xp base data as per the ortho4xp settings) , near Braşov in Romania as it happens, and the terrain height data transfers fine to the G500 so I suspect that it is related to the custom mesh which I think ORBX include in the true earth scenery.
all the best
mark