I have recorded a multi camera wedding in 1920x1080 (1.0 pixel ration). I have a nested sequence with the same ratio where I then used the multicamera feature to make the cuts between shots. I watched the entire edited version and did minor color correction inside of PPro. Then I decided to have the video fade in at the beginning and used the Dip to Black video transition on the first video clip and PPro squashed the entire rest of the sequence into a letterbox look adding black bars at the top and bottom. The titles I added before the footage looks normal, but if I drop the same transition to fade in the title, it looks squashed. Since the entire background is black at this point, I can't see if it added black bars to letterbox, but I am assuming it did as well. I removed the transition in front of the first video clip, but the entire video is still squashed into a unneeded/wanted letterbox situation. The original files and sequence have the same ratio, the letterboxing only occurred when I added the transition, now it won't go away. The original nested sequence still looks fine, but I really don't want to redo the entire multicamera editing process... And even if I did, how do I fade into the video if the transition is making it letterbox?

New Information:

My entire timeline is yellow across the top before I add any transitions. Once I add a single transition anywhere in the timeline, most of the timeline goes red across the top. It still looks normal though. It is when I render, that everything gets squashed into the unnecessary letterbox. Why would one "Dip to Black" transition make all of the different clips need rendering? And then, why would it squash them into a letterbox look when the clip and sequence settings are both 1920x1080 (1.0)?

I suggest you use a simple cross dissolve to fade in and fade out. Dip to black should be used only between the clips, as it fades to black in the middle of the transition, regardless of whether it is applied between the clips or at the end of one.

As for why you'd experience the effect you're talking about, I have no idea.

I used the cross dissolve and did not have the same issue, so thanks! Weird. I also found that if I would export the video without rendering, it did not squash it as well. Something happened with the dip to black and rendering... Hmmm.... Strange since I have used it before with the same hardware/software, just different video clips.

You can fade in from / out to black by setting 2 keyframes on the timeline brightness line and adjusting the brightness line to 0 at one end and full at the second keyframe or vice-versa...quick to do and affects nothing else...

i've used that technique, works better/faster than fade to black

Thanks! I will use that if I get any more craziness.