-
Maybe I'm misreading you but you don't drag the cursor along the road. You create a start point and then a waypoint and it automatically creates a route between those two points. shortest distance by default, or most popular route if popularity is turned on. If it's going a funny way then just add more waypoints along the route you want and it'll sort itself out.
There has been problems with some UK roads where the builder doesn't want to route down it, but again, spamming more waypoints fixes it in my experience.
Colonel_of_Truth
No, I don't get that far. As I'm dragging the cursor on the road I want, the grey line starts going elsewhere. It chooses it's own route.