I have the same issue and have for about a month now. I’m a registered Adobe ACE in Premiere Pro and I still can’t figure it out. It’s almost random, sometimes it happens and sometimes under the same circumstances it disappears. Sometimes it’s in my timeline and sometimes only in the render, and then sometimes in the render but not the timeline. It’s cray annoying. I called Adobe yesterday and they actually hung up on me! I was even being nice lol.
But so far it’s definitely any coloring or image effects on an adjustment layer. Once I turn that off and move coloring to individual clips then I have a 75% chance of it rendering correctly.
I’ve updated everything including graphics cards, tried different computers and it still happened, tested RAM and hard disk, uninstalled and reinstalled Premiere CC2014, you name it I’ve done it. Seems like the issue is here to stay until Adobe magically fixes it with the next update. Very un cool.