Exporting allplan models in IFC format does not work. The generated models have wrong levels. I have tried in several projects with the same result. In attachment A1, the original Allplan project level system.
Attachment A2 shows the level system resulting from importing into Allplan the same project, previously exported as IFC, directly from allplan. As you can see, the levels correspond correctly.
Attachment shows 3 the import in Allplan of the IFC generated by bimplus.