I am not considering this to be a bug. Behavior when the rolling stock ghost was drawing connections was causing some subtle crashes in multiplayer when the rolling stock ghost was on latency surface for the latency state. This rendering was disabled for ghosts and simulations because that was one of the most sane ways of fixing which would not change half of the rolling stock rendering code. The fix appeared first in the 1.1.27.
So maybe the solution would be to draw all connections for placing the rolling stock the same way when you hover mouse over completed train? In this state, one is not sure if the rolling stock would be connected after placed, i know it snaps whe you are placing it near to the train, but indicator is more convinient then shaking with wagon around to see if it snapped and to be sure it will connect.