Black frames with play buttons showing on videos!

I’m using Prezi Next on a Macbook

When I present my presentation, when I get to the videos embedded into my canvas and play them, the first frame shows a black screen with a play button and the last frame also shows a black rectangle with a play button.

When playing videos, moving to the video on the canvas should show the video static with the first frame of the video displayed and when the video ends it should freeze on the last frame of the video.

Just like in Classic.

Please can you fix this right away?