course page not working

I installed LearnPress on a new website 1: all-courses-page
https://leatherbagsacademy.com/courses/
2 ánd on subdomain: 
https://leatherbagsacademy.marablu.com/courses/

Only installed Learnpress, Divi, and 3 other quite common plugins on both exactly the same. The all-courses-pg work on both.

But: the link to the individual course with curriculum:
1 page remains empty: 
https://leatherbagsacademy.com/leatherbagsacademy-cursussen/sample-course/
2 and on subdomain I can see the course + curriculum:
 https://leatherbagsacademy.marablu.com/leatherbagsacademy-cursussen/voorbeeld-cursus/

What could possibly be wrong? All the layouts etc I imported exactly the same…
Also on another website had the same problems.

The page I need help with: [log in to see the link]