Jetpack: Stats don't show proper page views

Hey folks,

I am quite puzzled: I run several sites with WordPress and Jetpack and up to now stats were always right and reliable as far as I can tell. Now I ran into a strange problem and have no clue about the root cause for it.

Lately I migrated a blog from wordpress.com to a self hosted solution and bought a redirection at wordpress.com. The new blog uses Jetpack to provide stats. Page views for old posts are displayed correctly, as far as I can tell.

Yesterday we published the first post on the new blog. And now we face the puzzling fact that page views does not work properly: All traffic to the new post is shown as traffic to the start page, even though we know for sure that is was generated by clicking on the right permalink.

Anyone encountered this before? I got no clue as to what the reason might be. I run quite a lot of plugins, including WP-Stats-Dashboard.
Frankly, I have no idea where to start in order to find out what actually is happening here. And thus I have no idea which additional info might be necessary here to find the answer.

Cheers
Anders