Hi all,
Thank you for sharing your opinion about the issue!
I made a simple stair, based on what I understand in this case:
As you can see, the stair is linked to the ground floor and the 1. story. It extends 300mm below the ground floor. The cut plane is at 1 meter. But the display is wrong. This is because the Floor Plan Display for "Relevant Top Story" is set for showing "No Break Mark: Visible".
I believe something similar might happened with your file. Could you give it a check and let me know about the result?
Looking forward to hearing from you!
Best regards,
Minh
Minh Nguyen
Technical Support Engineer
GRAPHISOFT