Automatically creating a slab at the correct height in ArchiCAD


I’m trying to automatically create ceiling finish slabs using favourites. I’ve got a favourite for a slab set with the correct height, but using that in Grasshopper causes the resulting slab to be placed at ground level. There seems to be no way of pulling the height data from the ArchiCAD favourite either, as the settings I can access using the extract slab settings component is limited.

Is it possible to use the height in a slab favourite to place a slab?