Hello, I need help

I have been working on Storyline for more than 3 years and I sometimes encounter a problem that after I finish creating a training course, I upload it to Moodle (an open source platform). Some users while entering and starting to review the course, the show stops, that is, for example, I have a course with 23 slides, and when it reaches the 18th slide, it stops and a sign appears as if it is loading the page and does not return until I had to close the course completely .. Previously I thought that the problem was in that slide and after that I deleted it and discovered that this problem I face in different slides is not necessarily in that slide. Please advise, because we are a training institute and rely on online courses, and now I have uploaded a new course and I am facing the same problem.