We need to go to edit mode and modify the Walking Line polyline, and possibly the Numbers (each can be individually selected, moved and rotated), plus the "DOWN" text.
This is the result, which is almost perfect, except for the fact that it is not possible to hide the Floor Plan representation of that last Tread which we hid in 3D. Unfortunately, this is a limitation, because the Stair Grid is generated automatically, and it is not possible to individually select and hide Tread edges and Riser lines.
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-Ac27