When you export to SAT format it splits any closed edges or surfaces in half, so for example if you have a cylinder and export it to SAT when you reimport it you'll see it's in 2 halves instead of just one closed surface.

Also during SAT export it does a "ShrinkTrimmedSrf" to shrink down underlying surfaces down to their active trimming boundary area.

When the split happens it means that there is no longer any "seam" edges in the model, probably whatever problem you were running into involved something about seam edges. Or possibly if there were some self-intersecting bunched areas outside of the active trim boundary areas the ShrinkTrimmedSrf part can throw those pieces out.

- Michael