In this scenario, I have a Square Tile Object with all the summer buildings and trees and I want to duplicate it in a winter Sq.tile.
Crash on initial switching between terrsets:
After starting a new tile, I cannot switch directly, either way, between a summer tile and the winter tile without the OE crashing. (I have not placed any speedtree objects in the winter tile yet.) The work-around is to select New and set the properties to match the desired tile and then open the tile without saving.
Crash resizing window:
After the tile is loaded following the switch between summer/winter, the first time you resize the OE window, it crashes again. The work-around is to relaunch the OE after the tile loads and before resizing the window for the first time.
Once the tiles are stable, the crashes are gone on subsequent launch. This leads me to suspect that the speedtree files aren't created at the initial save.
Anomaly 1:
When I switched between the winter SqTile to Summer, my speedtrees were invisible until after I relaunched the OE.
Anomaly 2:
In one of my early launches, the perspective of the view was skewed. The round fuel tank, as an example, was oblong from any view point.