Movie not preview

I have a problem. I'm loading a movie into Storyline 3. The movie is 250 MB. I've used 1GB movies before whitout, so 250MB shouldn't be a problem.

The movie is added to the timeline and is 7 seconds long. The movie does not play in the course preview (pager is blank, not see movie). I have never uploaded videos that are 3,5 hours long. I know the timeline is limited to 1000 seconds. I prepared the audio in Camtasia, which is 4 hours long. I add audio to page and I extended the timeline over 20,000 seconds. I added a video on a new slide (20,000 seconds timeline) and the video adapted the tiomeline to its length (16000 secound). Great. However, the video is still not showing in project preview.

I can edit the movie in Storyline, for example: add a watermark etc and save new movie. It works. I can preview video in Storyline: Storyline > Options> Perwiev. The movie does not work only in project preview (page, scene, project). The movie does not work after exporting Scorm and HTML.

I try to make it in new corses and I still have tehe same problem. Movie workd in Storyline but not in preview.