Tread line for stair is vanished

[Anonymous]

Dear Friends,
I am having an issue with my stair. All lines at visible parts have removed(See Fig-1). Their outline can be seen after selection (See Fig-2). I already checked the possible parameters. For example.
1. Pen Set & Pen
2. Different Model View
3.Graphic override

It's almost 6 hours I am stuck with this issue.
Here is the pln file for the stair. It will be a great help if you can take the time to check my pln file attached here.
https://drive.google.com/drive/folders/1HoPemWealilZupHBdaPEd_ktOwr1ReUG?usp=sharing

[Lingwisyer]

Check the stairs floor plan overhead setting.

[Anonymous]

I tried my best but I can't fix it.

[Laszlo Nagy]

The combination of the below two settings can cause Stair Treads on the visible portion of a Stair to not be displayed: