I am not new to XPages, but have a situation where I have a customer with a Domino 8.5.3 server and recently set up their developer with the 8.5.3 Designer client to learn to develop XPages. When they work with a local database, previewing a new XPage works fine. But when the database is on the server and they create a new XPage (really simple, just some text) and preview it they get "Error 403: Item not found exception". Previewing existing XPages works fine. They have Designer set to "Build Automatically", have Manager rights to the database, and have rights on the server to run XPages (all the usual stuff). Plus, occasionally this also happens to me (but most of the time it works fine for me).
Anyone seeing similar fluky behavior with previewing newly created XPages?