If anyone stumbles across this post having similar issues and having the same problem where Orbx seems to have stopped responding and offering ideas, I solved it, somewhat by accident.
Today, I (finally) updated to the latest hotfix (#3) for p3dv4.5. I updated the client only using the prescribed method.
I also deleted my cfg and my shaders to let p3d rebuild those after the fresh client install.
Then, after a short flight, I closed the sim, applied a PTA preset, and was off flying again!
After a flight, I decided to try the various airports (KBVS, PAJN, PAVD, PAWD