R2018.3
18.4.0
IFC4RV1 (but also IFC2x3CV2)

any idea why two identical ramps are differently exported?

They are in IFC exported as:
1) container IfcRamp containing an IfcRamp
2) container IfcRamp containing an IfcRampFlight

The Export Options are on purpose all on "IfcBuildingElementProxy".
The export as IfcRamp of this System Family is hardcoded.
No "IfcExportAs" is used.
(BTW it is not making any difference if the Category and all subcategories are set on IfcRamp in the Export Options Panel)

 

Last edit: Dirk Van Rillaer 2018-06-26