You have unchecked the "By Model View Options" checkbox so the Floor Plan Representation of the various components of your Stair will have to be defined here in the Stair Settings Dialog.
On the left pane, under Floor Plan Display, activate the Grid page.
Then on the right, at the top of the Grid Components Setting panel you will have a large button using which you can choose which of the various portions of the Grid appear. You can select an option for Relevant Stories, Above Relevant Stories, Below relevant Stories individually.
Loving Archicad since 1995 - Find Archicad Tips at x.com/laszlonagy
AMD Ryzen9 5900X CPU, 64 GB RAM 3600 MHz, Nvidia GTX 1060 6GB, 500 GB NVMe SSD
2x28" (2560x1440), Windows 10 PRO ENG, Ac20-Ac28