Empty page needs refreshing

Hi!

First the subject, I have question about:

<form name=”continue-course” class=”continue-course form-button lp-form” method=”post”
action=”https://www.business-wise.nl/cursussen/sample-course/lessen/lesson-6/”&gt;

<button type=”submit” class=”lp-button button”>Hervat</button>

Clicking the button (submitting while logged in and enrolled), results in an empty page that will only show the lesson(s) when repeatedly refreshed.

What advice do you have for me to resolve this?

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