SketchUp to UE4.24.3

Hello all, I’m an architecture student and new with UE4. However I’ve been learning from tutorials on Youtube and I tried to build a project… So far I finished the house model on Sketchup and it looks perfect but when I try to export it onto UE4 with Datasmith somehow I get missing geometry such as the floor and a few walls and stairs… Any help please ? I really enjoyed UE4 on Youtube and I really like to create my models for my studies and work using UE4. Thanks in advance and hope you are being safe during these horrible COVID-19 times.
P.S. I’ve uploaded attach ments of both UE4 and SketchUp screenshots so you could compare.

In the SketchUp top bar, go to View > Face Style > Monochrome and make sure all of your faces are oriented with the white side showing.
Unreal engine reads the back side of SketchUp geometry (shown as grey in monochrome mode) as transparent.