Content disappears on WordPress page
I' searching for post regarding my problem since 2 hours, but I can't find a solution.
I installed the H5P plugin (1.10.1) for WordPress (4.9.5.) according to the instructions and everything works perfectly - no error message or anything. But the H5P content can only be seen for a very brief moment when the page is loaded and then it's gone. I tryed several content types (including example-files) in different browsers on different devices - same result. And there is co extra code or anything (like tabs).
There should be content here for example (text page), multiple choice and blancs:
Do you have any idea what could be wrong?