It’s important when you export a Revit model to IFC that the following conditions are met:
Export with “Current View Only” option
Parts must be visible in the view
If the “Split Walls and Columns By Level” option is chosen, then wall parts will be assigned to the appropriate level as determined by their spatial position
Be aware:
Parts import / export done for all categories except Roofs
Parts import from IFC : only geometry is imported not the parts information
