Hello:
I can move,change height and delete.
Cannot "GET TRACK" if placed before H4.
I can place the same track/bridge and come back later and GET TRACK (Highlight).
Track /bridges will not highlight if placed before H4.
There are some splines which give problems when elevated 10 metres, or more, above relative ground level.
They will behave again if the remove gradient button us used to flatten them, or the height is reduced to less than 10m. It's then just a simple matter to deal with them as you want and re-elevate them to the required level when done.
Advance apologies if this doesn't solve the problem because I've no idea what H4 means.