I don't see the stair in either image and both floor plans look the same so maybe you sent the wrong lower floor.
I don't know what stair object you are using but you should be able to select the stair and in the floor plan setting select "Show on Home Storey and one Storey Up"
Cheers,
Gerald Hoffman
“The simplification of anything is always sensational” GKC
Archicad 4.55 - 27-6000 USA
2019 MacBook Pro-macOS 15.0 (64GB w/ AMD Radeon Pro 5600M GPU)