FSX Buildings Disappear and Reappear in FSX with Mesh

Kind of an unusual situation that I never had when in FS2004. I use FSX now as well and was using the free BlueScenery Photoreal mesh for most of Idaho. The folks at BlueSky were kind enough to also include airports edited with ADE so the airport matched the new elevations if necessary.

I have since purchased Megascenery Earth v2 for the State of Idaho and disabled the Bluesky Mesh, but left the Bluesky airport edits intact and displaying. In almost every case, the airports still match the terrain and I haven't found a single runway "sunken in" or on a "plateau"...yet. What puzzles me, is the person who edited the airfields for Bluesky with ADE sometimes used the stock buildings at the airport and sometimes used objects from a different library.

The stock buildings disappear and reappear in the sim, depending on which way you look with the hatswitch on the joystick. In almost every case they are always visible at a distance during approach, but the closer you get the more likely they will disappear and then suddenly reappear. In one case, at U70 Cascade Airport as I was taxing down past a line of buildings, as long as my view was straight ahead the buildings were visible. As soon as a panned to the right to look directly at them out the aircraft side window they would disappear, only to reappear again once I was looking straight ahead.

It only seems to be stock/default buildings that do this. Any buildings placed from 3rd Party Libraries do not seem to do this. I assume it is an elevation problem, yet when I look at the elevation of the third party objects and at the stock objects they are both set at 0 elevation.

Because the Megascenery (and the Bluesky Scenery before that) removes or "blocks" the autogen I have started adding trees and some buildings back in to the scenery in and around the various airports. Some of them are high mountain airstrips and even though working on the "flat surface" of the ADE surface (not sure what else to call it) they always seem to display fine and continuously, even though they may be 300 ' vertical up the side of a mountain. Stock items do not.