We have designed a SharePoint 2013 theme for our client and are trying to export this theme to install to their farm using the design package exporter (/_layouts/15/DesignPackageExport.aspx). Some of the content types we have created were exported, and some were not. The same is true of some fields we had created. I extracted the WSP that was created and checked the ElementsContentType.xml file and two of the content types are missing. We didn't have any error messages. The content types that are missing have the document template /_layouts/15/NewPageLayout.aspx and the ones that were exported have the document template /_layouts/15/CreatePage.aspx, could that have something to do with it? Other than that I can't see any differences in the properties between these.