Hey Jordy!
I’ve been in contact with the developers of the theme and they didn’t have a clue what’s going on as they didn’t get the same problem. So I created a new test page and installed the theme, the other necessary plugins and WP Retina 2x and it is working fine.
I’ll just re-install everything and go from there. Probably was a one time thing.
By the way, love the photos of Japan! Man good work, keep it up! Fantastic stuff!! ??