When you tried to underlay a floor only doors and windows were visible.
Revit site plan showing floor plan.
In the main floor level the bottom of the primary range is set to main floor with an offset of 1.
About the view range the view range is a set of horizontal planes that control the visibility and display of objects in a plan view.
About plan views in a 2d view display a floor plan a reflected ceiling plan or structural plan.
In this video i show you everything you need to.
This issue occurs because there is an incorrect view range in the main view.
You can find this tool in view tab create panel plan views drop down plan region.
Under floor plan views select the level on which to base the site view.
Click view tab create panel plan views drop down floor plan.
Under floor plan views select the level on which to base the site view.
Create a site view as follows.
In the new plan dialog clear do not duplicate existing views.
Get this revit file here.
Click view tab create panel plan views drop down floor plan.
A floor or slab will be visible in a plan view if it is partially above the view depth or if it is within 4 feet approximately 1 21 meters of the bottom clip.
If the view range intersects the geometry of a level in your main view that level cannot be used as an underlay in the main view.
You will need to define the plan region using sketch tool.
Please like this video.
About plan regions to define multiple cut planes within a plan view use plan regions.
In the project browser rename the newly created floor plan view to site.