Muffin Builder not working correctly on verktoypartner.no

All plugins, wordpress og theme and theme plugins are updated to the newest version.

To reproduce the error, I copy the contact section so it should span in two rows like this:

But the result on the front end is like this:

When I look at HTML source, or Web Developer Tools Inspector I can see that only two <div> with class "one-fourth" are generated. It looks like the HTML of the section is not correctly rendered, there should be four items with 1/4 in with, but it generates only two. This does not look like CSS / Javascript error but a bug in Muffin Editor.

Please help.