Interactive video, course presentation not loading

Some content is suddenly not showing anymore

1. Steps to recreate the bug: created new interactive video, course presentation and/or personality quiz and also tried uploading an example. Putted it in a page and in an unit of WPLMS. In all cases nothing shows up. An existing documentation tool does however work well.
2. Error message if any: none
3. Platform you're using: Wordpress latest version running WPLMS. Enabled en disabled W3 cache plugin and the bulletporff security plugin
4. Mobile or Desktop: desktop
5. Browser: Chrome, IE
6. H5P plugin version: latest version. All versions are updated
7. H5P content type version: interactive video, course presentation and personality quiz
8. Screenshots if it's a visual problem

All three did work and were visible earlier. No new plugins are installed (except Bulletproof security plugin).

Tried the solution mentioned in: https://h5p.org/node/119573 (adding code to wp-config.php and uploading example). Did didn't work.

/*
 * @link https://codex.wordpress.org/Debugging_in_WordPress
 */

define('WP_DEBUG', false);
define('WP_DEBUG', true);
error_reporting(E_ERROR | E_WARNING | E_PARSE);
define('H5P_DEV', true);
define('H5P_DISABLE_AGGREGATION', true);

/* That's all, stop editing! Happy blogging. */

Also after editing an H5P and click creating, it does not show an example of the created content. Even the documentation tool (which does show in an page!) is not showing after editing and clicking create (it doed however show the standard bar that's underneath the content).

Can anybody help me out?

Thanks