I am running P3Dv4. I have all ORBX sceneries. All bgl's are off via forum instructions, including compatibility file from ORBX. My issue is, when viewing from tower, I see airport tram disappear into ground. The road running parallel to the tram is also sinking into ground. All other elevations are where they should be. No floating jetways, no plateaus. I had this problem awhile back,and I can't remember how I fixed it. THX S. Sumner