Some, especially older presentations, may contain an outdated picture format called WMF (Windows MetaFile). When you use such picture on a slide, it will be removed during the import into CloudVOTE.
This is because our online "parsing" library is not compatible with this format.
Simply replace your WMF images with JPG, PNG, GIF or any other modern format and the import will work just fine.
Let us know if this solved your issue and/or answered your question below...