How do I view construction/gridlines in the 3D Structure scene view above the Base level?

Scene content

The scene content controls what is to be displayed in the active scene view.

Project Workspace > Structure tree - Levels branch

The Project Workspace > Structure tree - Levels branch allows the user to decide via the Properties window if a specific levels construction lines/grid is to be visible in the 3D Structure view.

You can select an individual Level (i.e. St.2 etc.) to turn on or off the display of the gridlines on that specific level.

You can select the Level branch to turn on or off all the gridlines on all the levels (i.e. St 1, St.2, St.3 etc.)