Posts seem to work fine in draft mode. Publishing makes them disappear. Published posts can still be seen in the All Posts list. But trying to edit them returns the following message in the main section: "The page you requested was not found we suggest you to go back to HomePage." After publishing a posts, settings stop changing the content of the post.
If I leave the post and go back to the post editor, post Settings are no longer accessible. The underline shows Settings as chosen, but the widget options show below.
Similarly, the frontend of the website can navigate to post categories, and the posts are listed in the categories list. But clicking on a post returns "The page you requested was not found we suggest you to go back to HomePage."