Rise does not show start frame in videos

Hello, 

I created a Rise course and included videos that I had made using Articulate Storyline. I exported the videos as MP4 files and implemented them in a video block. 

The problem is that not all of the videos show a starting picture; they are all presented as grey rectangles. One video is different, however, and was created in the exact same way as the others. 

 

What I have already tried: 

• Checked the settings, but nothing could be changed there.
• Exported the videos again in Storyline and exchanged them in Rise in the video block.
• Removed the existing video blocks in Rise and created new ones.
• Checked if naming in Storyline makes a difference.
• Checked if the slide settings in Storyline are different.
• Implemented the MP4 files into a new Storyline slide and set a poster frame. I exported the slide as an MP4 file again. I implemented them in Rise again.
• 

   

• I deleted everything and implemented the exported MP4 files from Storyline (without a poster frame setting) into the Rise course. Again, the last video shows the starting frame even though no poster frame was set.

I have no idea why the last video shows a start frame and the others don't. I couldn't find any difference. 

Can someone help me ?

 

Kind regards, Elisabeth