It could be because you are using 21.
I found a few issues with stairs and rails in 21 so I never used it and went straight to 22.
I just tried in 22 and if the rail is associated to the stair and upper slab, and the rail is set to use the stairs display settings, the break mark matches the stair.
This image shows the upper floor with the ground floor as a trace.
Barry.
One of the forum moderators.
Versions 6.5 to 27
i7-10700 @ 2.9Ghz, 32GB ram, GeForce RTX 2060 (6GB), Windows 10
Lenovo Thinkpad - i7-1270P 2.20 GHz, 32GB RAM, Nvidia T550, Windows 11