Thanks for responding Sean. I'm sure it's something I may have done rather than a TrainSimulations fault, because like you I've never seen anyone else posting about this. Unfortunately I don't think I'm seeing just an occasional overlooked buffer - For example on the Ruel route (which was ok before I d'loaded Mullan) there are 9 tracks without buffers by the old roundhouse at Capreol Yard. (not the ones ending at the warehouse doors.) Not to worry, the routes are great and I'm having a lot of fun running them.
Dell desktop. Intel i5 3.3 CPU. 8GB RAM. Nvidia GT710 2GB graphics. Windows Pro 64bit. RailDriver.