3D .stl not exporting correctly to Simplify 3d

Model created in newest version of Sketchup isn’t exporting to .stl and importing into Simplify 3d. A basic box or whatever does, and prior to this model, it did always export fine, but now, it doesn’t export all of the model to Simplify 3d.Attached are screen shots. Thank you in advance

RemoteBox1.pdf (181.6 KB)

How about sharing the SketchUp model so we can see what you’ve got going on?

From your screen shots it appears you are missing faces that would be required to make the shape “solid” and prevent it from printing. It appears you have what I’ve tried to reconstruct on the left and what you need is on the right.

Seeing the SKP file would help to identify exactly what the problem is, though.