There're thousands of add-ons on the Web for the classic FSX and Prepar3D v1 to v3. Take off from anywhere in the world, flying some of the world’s most iconic aircraft to any one of 24,000 destinations.
I had a similar problem which I solved by changing the order in which Addon Scenery loads. I suggest you get the freeware program named Config Editor and experiment with changes in the order in which things load. Good luck.