Room bounding element doesn't get RelSpaceBounding relationship

Hi,
Working with IFC2x3 TD1, Revit 2020 and the latest Revit-IFC add-in (20.2.0.0), I am trying to get watertight 2nd level RoomBounding element in IFC throught IfcRelSpaceBoundary. My Revit file, see attached document below (from imported IFC), recognises my Windows as room bounding but they aren't exported as such in IFC.
Could you lead me as to how is room bounding relation is created from revit elements and rooms ?

[Revit_for_Lesosai.zip](https://github.com/Autodesk/revit-ifc/files/4972046/Revit_for_Lesosai.zip)

Best Regards,

Yorick

Reproduce the report with the attached Revit_for_Lesosai.zip using Revit 2020, IFC2x3 TD1, and add-in 20.2.0.0; inspect the exported IFC for IfcRelSpaceBoundary entries involving windows. Done means determining why room-bounding windows are omitted and correcting or documenting the expected relationship.

Written by the indexing model from the issue text.