Long story short, Revit has problems with colours and materials. This has cropped up many, many times already on this forum, and on other forums.
We really should just collect all these links in one place so that the next time we can just point them to the list, and you can just see which one applies to your scenario. I’ve actually converted most of the conclusions from the forum posts into Revit bugreports, which I’ve linked below.
- Materials break depending on what type of geometry it is
- Revit uses incorrect IfcPresentationStyleAssignment in IFC4 leading to missing colours
- Revit ignores material properties / doesn’t actually import materials
- Revit doesn’t actually export materials, by the way
- Sometimes IfcRelAssociatesMaterial won’t export
- Duct fitting material broken
More reading:
To be a bit more constructive, would you mind attaching your IFC, and then we can review it to determine the exact problem? Once that’s determined, we can see what the fix is.