Captions on my videos don't show up

I set up a video using 10 still photos, and want to caption each one. I have been successful in the past, but lately, my last two didn't work. I did it exactly the same way, entering the text manually. Not sure why it won't work, but I find it very effective to use if its possible. Any help is appreciated.

Once the video is done, I edit it, and hit the captions tab, then generate the captions manually. Once done, I hit "save to video" and it just sits there. Then nothing happens on the video.

Help!