Because of some compatibility issues with the old IMVU Previewer and the 3DS Max exporter, some Content Creators (included me) are using the latest version of the IMVU Previewer to upload new derivable products to the IMVU Catalog.

So if you upload a derivable product on the IMVU Previewer and you see any error messages or find that there are missing elements (like materials) on the Previewer, please upgrade to the latest version of the IMVU Previewer.

If updating does not resolves the problem, please fill a support ticket HERE since this may be an IMVU-related problem.