Windows 8.1, moviemaker version 2.1.4026.0

I import photos (jpg), and movie files (wmv) into the collections box. While these are in collection box, I can select a jpg and it shows in the black video box on the far right. Also, I can select a wmv while it sits in the collection box, and I can see the movie and hear the audio in the video box. (please correct me on correct terminology for this video box).

The trouble I have is when I drag photos and movies into the timeline. They are both visible there, but when "play" is selected, and the bar starts sliding along, there is no picture visible in the black video box. Neither photos or movies. There IS however sound playing from the movies. Baffled.