If you want to make the opening an arbitrary extrusion, you can Alt-O with the wall selected to toggle openings (with the BIM Tool activated), then select the bright blue opening, in the Mesh Properties tab, click on "Update Mesh As Arbitrary Extrusion".
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I can replicate your problem, but it seems to only happen in Xbim.
I tried 5 other ifc viewers, and the window showed up correctly.
Could it be Xbim?
in fact, in the us.bim viewer it did not appear, but in the bimcollab.zoom and in the ifcopenhell viewer they did:
Is it because the opening has tessellation representation?
Maybe try to update the mesh representation of the opening as an arbitrary extrusion in BlenderBIM ?
how do I do it?
Yeah unfortunately some viewers don't support tessellation representations. It's a shortcoming in their implementation.
See relevant bugs https://github.com/IfcOpenShell/IfcOpenShell/issues/2499 and https://github.com/xBimTeam/XbimGeometry/issues/399
If you want to make the opening an arbitrary extrusion, you can Alt-O with the wall selected to toggle openings (with the BIM Tool activated), then select the bright blue opening, in the Mesh Properties tab, click on "Update Mesh As Arbitrary Extrusion".