So, are you confirming the problem at KDFW happens ONLY with the QW757 and not with default airplanes ? Have you tried other addon airplanes ?
The fact this doesn't happen with our other sceneries, it's because of the scenery is made (it's fully 3d, which allows for elevated taxiways, that our other sceneries don't have), this means is probably more sensitive to the how the airplane is made.
People have been asking elevated taxiways for ages, we always said there were lots of issues and side effects, this is one of them, there *are* some rough edges with an airport made to support elevated taxiways (the whole airport has to be designed differently, just to support them) so, there might be issues in some situations and/or with some addons.