New posts in subdirectory installs give 404 error on mapped domain

When I am logged in through the sub directory domain, and publish a post, then I get a 404-error when I view it on the mapped domain after it has been published.

When I log in to the mapped domain through, the post I just published is not even there!

It is like I have two identical sites operating independently of one another. Any idea what is going on here?

(For a while now I have been using 3.0.4 version of the Domain Mapping plugin. I just upgraded this to the latest version today. )