Rotten Tomatoes Rating not always showing up

I am currently building my library and add about 20 new movies every day for the past two weeks.

Until 2 or 3 days ago i would have a Rotten Tomatoe rating show up in the DialogVideoInfo.xml-view for every single movie i added.
Since then it is hit or miss, it will show me the RT rating for maybe 5 out of 20 added movies.

When checking the RT website all of them *do* have ratings, so it is not that.
Removing the movie and adding it again does not help, nor does refreshing it.

I am trying to understand the very basics of how all this works and am lost.
Is it the scraper not collecting the data? The skin not showing it?