Sometimes using the 360 tool or the walk around tool the model hollows out. Like a section view which I don’t want. As I move around the missing section changes
Sounds like the clipping plane issue. You can search for it here on the forum; tons of people are having issues with it.
Also, here’s SketchUp’s Help Article on Clipping Planes: https://help.sketchup.com/en/sketchup/clipping-and-missing-faces
Click link for GIFs.
Basically, keep the model by the origin and don’t make it too big or small, then it should be fine.
Also, rendering seems to not show clipping problems, but I think large models can cause rendering problems of some kind.
That or they walked into a wall or something.