KDP v3 Video Thumbnail not loaded?

I am having a problem with KDP 3. I found KDP 3 does not load the video thumbnail when the player is loaded.
In KDP 2, the player loads the video thumbnail when the player is loaded by default. I don’t see that in KDP 3. When KDP 3 is loaded and video is not autoplay, the player is just black instead of the video thumbnail.
I am not sure if it is a bug or I have to specifically tell KDP 3 to load the thumbnail. I couldn't find anything about that in KDP 3 API.

Here is KDP 3 demo in Kaltura http://www.kaltura.org/demos/kdp3/kdp3.html When the page is loaded, the player is black instead of video thumbnail.

How do I have the video thumbnail loaded in the player?

Any advice is appreciated.