Jetpack Infinite Scroll Bug

Hi

Whilst developing a theme for this site:

https://robrowettarchitecturalservices.co.uk

I kept running into a problem with displaying category posts. I wanted to display the thumbnail and post title only. However, with infinite scroll enabled the theme would display 10 posts as the code requested but after that it displayed the full post.

Any ideas why please? Is this a bug?

Rich