Export file incomplete

I am trying to create an export file for my blog, as I’m migrating it to new hosting. The old site is still using 2.7 (I know, I’m bad) but the new site is 2.8.4

The problem I’m running into is that when I import the xml file, all posts more recent than August 2008 are missing. Is there a reason for this? Why would the export file only export a certain number of posts but ignore the most recent ones?

Any help on this would be greatly appreciated.