Dissolve transition seems to add a black frame in between clips

I have been getting frustrated as of late with the Dissolve transition added between two clips. Normally, I will have multiple clips selected and add the dissolve transition to them all at once. Some will be smooth, as intended, others will have a brief fade to black in the middle of the transition. I've double checked to make sure there are no gaps between clips (using the step ahead one frame button). Below is a brief segment of a video that shows the black during a transition or two and the last transition being clean and smooth. Where is the black coming from?

https://www.dropbox.com/s/y3cb2watbtir972/Levi%20Court.mov?dl=0

Any help would be appreciated1

Trevon