I know this topic is old, but I've just had the same problem and found a fix for it should people still have the same issue.
For me, turning off the instancing engine did not work, and to be honest I'd rather not turn it off since the scene I'm working on is huge. So instead, I added a MaterialByElement modifier on top of the railclone, set the random distribution to a high number and voila, it works!
Adding the modifier does prevent the point cloud display from working though, but that's a small sacrifice since displaying as boxes work just fine.
Hope this helps.