Going to try to explain this simply...
I have three videos, each with their own audio and their own adjustment layer (for color correction).
Between video 1 and 2, I can cross dissolve both video 1 to video 2, and adj layer 1 to adj layer 2, exponential fade from audio 1 to audio 2. Everything is fine. Transitions exactly the way I want. (In this case, both videos are small cuts of longer footage)
Now, between video 2 and video 3, a cross dissolve won't work (figured that out after a moment of being very dumb) because video 3 needs to start right at the beginning... nothing to "cross" dissolve from. So, manual dissolve. Works fine. Expo fade in audio, fine.
But, because of how I did the color correcting on adjustment layers, I have to cross dissolve them as well. Worked last time.
... and this is where I'm utterly confused.
When I apply a cross dissolve between adjustment layer 2 and 3, for some reason I do not understand, in the transition there is a freeze frame of the middle of video 3 that lasts until the end of the transition, wherein video 3 resumes as normal. It's as if video 2 is being cross dissolved from just one frame of video 3. And a frame somewhere in the middle of it.
This doesn't make sense to me. The adjustment layer isn't linked with the video at all. It's just color correction. How and why is it affecting the video playback?
I have to find a solution tonight, so I'll probably end up doing something different (like just adding the color correction to the video), but I'm very curious as to what is happening. If you need more information, just let me know. I'm saving this file independently just to try to figure how what's happening.