makes no difference whether it's ticked or not when laying track the height remains the same as the starting point height for both ends
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S20 or Classic?
What are you ticking?
In S20, place a fixed track object, switch to Free Move tool, enter the height value in Tool options, select the end vertex, click on the icon and choose Apply height to this vertex.
I did notice a bug using the Fine Adjustment tool anchor so will get that fixed.
