I think this is a limitation of IFC rather than a bug in AC.
I had a similar issue with doors being random colours from the palette that was used for different elements of those doors and as I understood IFC3 can only have one colour per element and IFC4 is far from being a standard yet.
If all you want is a colour correct 3D model to share, perhaps a BIMx will work?
Erwin Edel, Project Lead, Leloup Architectenwww.leloup.nl
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