I have make a brand new wordpress installation. To avoid dragging the old problems.
I just installed the plugins that are used to make the courses.
I imported the old course, but it is not fully visible.
When you first start even the short code worked, then after the usual procedures - Permalink - configuration procedure of the summary of the course, they started working.
But the units are not visible. And there are also errors of design visualization.
One of the units is a completely blank page.