To view zone spaces in 3D:
Go to View > Elements in 3D View > Filter and Cut Elements in 3D and make sure the “Zone” checkbox is selected.
Use the Model Panel of Zone Settings to choose a Surface for the Zone in 3D.
See Zone Model Panel.
Note: You may wish to display 3D Zones as solid bodies in shading mode, and all other elements types in wireframe mode. To achieve this effect, apply the predefined “Show 3D Zones as Solid” Layer Combination.