As of version 1.5.0 you have to set the feature refreshcache to true explicitly (directly in the settings.yaml or with the checkbox in the settings area). This will make sure, that the cached content-tree, the cached navigation, and the sitemap will be recreated every 10 minutes. If this feature is activated, you can also trigger the recreation of the cache with a hard browser refresh when you open your typemill website.
You have t o follow some naming conventions if you create your content files manually. The files are ordered by a numeric prefix like 01-, 02-, 03-. Posts are ordered by a date-prefix like ....