If detail pages of your Custom Post Types return only “404 Nothing Found” page and you are sure they are correctly created and available in WordPress admin side, it’s highly possible that permalinks structure has to be resaved in your WordPress.
Simply go to WordPress Settings > Permalinks options and save again your preferred permalinks structure.
Not found detail pages of Custom Post Types – 404 problem
Updated: July 29, 2016
Please do not submit multiple tickets for the same request, as this does not result in a faster response time.