there is a bug while exporting/importing geometries generated in geom, not sure up to what extend it goes, but at least with divided cylinder there is an issue in the geometry created. as if it is exported and re imported again, it does not produce a correct result.
to repoduce this:
- create a diviced cylinder with square option (this creates a flat content of 5 SOLIDS, shown in inspect → what is)
- select it, file-> export->step
- import the exported file
- check the geometry with inspect->what is? (what is command will show that the imported object has a flat content of 2 SOLIDS and 3 SHELLS