I suspect you are very far from the origin and that your exported mesh is being shattered by floating point computer math fuzz at that distance. This is typical of what happens to Rhino meshes created far from the origin. What tends to confirm my suspicions are the coordinate numbers you see in the lower right corner of the status bar in your image - those are absolutely huge…
If that is the case, try moving your model close to 0 and re-exporting.