My brief experimentation with MSTS didn't last long.
Thanks to the Demex mod was able to get a route extracted and set up the terrain etc.
Unfortunately there the success seemed to stall. On opening the little test route I went to place a Sound Source as otherwise the editor doesn't scroll properly. Despite getting the item in the selection box and the white cross on the terrain, no placement occurred. The cursor was moving (eventually) but not putting down an object.
I removed MSTS Bin (as I read this can cause issues with the RE) but made no difference.
Unless anyone can suggest a possible solution, sadly it really is time to draw a line under MSTS certainly so far as any fresh build routes are concerned. The worry has to be for the Open Rails guys, as fewer people have the old hardware that MSTS is happiest on they are going to actively need to think about their own custom editor(s) going forward.
Well it was a little distraction for a couple of days, guess it's time to get back into TS2014 and Trainz building.