Well Don. Also took a good look at your scenery.cfg and terrain.cfg.. both look fine.
Everything else looks correct, the terrain.cfg entries and numbering, the placement and priority within the scenery library is correct and from this can tell that the FTX insertion points are correct.
The only thing I am not sure of if there is any mesh or LC in Flytampa scenery but it would be very odd if that would have any bearing on Tongass.. I don't think so. I guess to be sure, it would be best to turn off that Fly Tampa in your scenery library, and close out the sim.
To give all a reset of sorts: after closing out the sim, delete the shader folder
(C:\Users\Norm\AppData\Local\Lockheed Martin\Prepar3D v4\Shaders)
and and delete the prepar3d v4.cfg located at C:\Users\Norm\AppData\Roaming\Lockheed Martin\Prepar3D v4.
Then restart the sim. As it starts up, the updated shaders will rebuild and the prepar3d.cfg will also rebuild and set the sim to default settings. (normal settings for graphics etc: this will fix any entries that may have got messed up in the prepar3d.cfg file).
Definitely a weird one. Give this a shot and report back.
Norm