The problem is confirmed to be fixed in P3D V5, if you still have elevation problems with the latest update, they are caused by something else, which explains why reinstalling KFLL is not fixing it.
If you have anything from Orbx installed, be sure FSDT KFLL gets an a higher priority on the Scenery Library, which on P3D can be usually done with Addon Organizer.
Also, if you have an OrbX product that adjust the terrain altitude, be sure you run its configuration utility to exclude KFLL from the adjustment.