The host increases drawing speed with a technique called backface-culling. In short each face has a normal and faces are only drawn if that normal points towards the user.
For a closed solid this always gives the right results as the front faces always hide the back faces. I'm not totally sure about your model, but it doesn't look solid so I guess it is a invalid stl. You can test yourself if it slices, if not that is the reason.
I have also seen stl files where the normal points in the wrong direction causing a similar effect, but they normally slice good if no other problems (non-manifolds) are present.
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