The online resource SketchUp 3D Warehouse (https://3dwarehouse.sketchup.com/) is an incredible source, but some models at times can look a bit odd when compared to the preview seen on the download page.
The use of SketchUp (.skp) models in InfraWorks does come with a minimum requirement, you MUST have Navisworks Manage or Simulate with the same release year as the InfraWorks release installed on the computer.
It is easy enough to use. Once the model has been added you will have to assign a TYPE and use the INTERACTIVE PLACING button. At times you will need to edit the scale of the model, typically at a factor of 12 or .0833.
Sometimes the building does not appear the same as shown in the preview. Upon placement, it may look hollow, transparent, or just plain odd.
Take a look into the connected Data Source Configuration and navigate to the 3D Model tab. Here you will find five checkboxes that should help you.
~Invert Orientation — Inverts the direction of the face normals that make up each surface of the model.
~Invert Transparency — Makes the transparent areas of the model solid and the solid areas transparent.
~Invert Up Axis — Flips the model upside-down.
~Flip Y and Z — Controls whether the 'up' axis runs along the Y or Z axis. Some applications use the Y axis as the 'up' direction while others use the Z axis.
~Override All Materials — Replaces model materials with a single uniform color that you select. You can enter the color as a hex code, or click the Browse button to pick a color from the palette.
This option is helpful if you have 3D features and want to depict them in pure form - similar to a physical architectural model where all of the buildings are white.
Source: Infraworks Help File
In the image below, Invert Orientation worked. Now the building model appears as a solic.
I have applied this fix when encountering issues with other types of connected Models and REVIT buildings. It now appears the way it should.