I use Sketchup quite lot for my designs.
The issues you encounter is one I have not had at all.
Slight geometry changes due to the mesh creation, sure, but not entire parts of a model ‘overlooked’ by Studio.
Keep in mind that Sketchup is more an architectural design program than something used for 3D printing…
In order to use it for 3D printing you need to make sure what you create is a SOLID model - either using Solid Inspector or by the model showing as solic in the SU Solid tools for merging and cutting.
I suspect your screenshot is a section view of the model.
It seems to be fine in Sketchup but there is only one way to make sure.
Dimensions can be a big problem as well, especially when exporting the model as STL.
Don’t blame Studio unless you KNOW the exported STL file is flawless 