I was having the same problem, and ran the Auto-Configuration utility in FTX. It moved both KMEM and KDFW to the disabled column. And that fixed the elevation problem.
However, I also run Aivlasoft EFB, and upon starting it, it said it couldn't find the BGL file for KMEM. Part of EFB shows the airport layout, including all runways, taxiways and gates/ramps. The airport is still on the EFB list, but won't load.
Any ideas on how I can fix this without dumping FTX Global?