Update:
I’m beyond frustrated. First thread was about simply documenting what I was experiencing–for posterity–as much for myself as for anyone else doing searches. Wasn’t really asking for any help unless it sounded familiar to someone. But now I am–some kind of clue, or something.
I noticed the other day the glitch (or better described as frame warping) in the Source monitor. Meaning, out goes the theory that it is related to graphics, alpha channels, framerate conversion going from 60 to 30 in the timeline.
Current theory? May have something to do with the way Premiere interprets the h264 codec, and specifically the 59.94 version of it. Maybe? Because I’m not seeing this anywhere else (e.g., FCP, Quicktime, Finder).
Testing of other outputs at 29.97 doesn’t seem to do it. At least as of right now in my small batch of testing. Our group has done thousands of videos over multiple years with the same workflow, and this issue has only popped up with the introduction of Apple Silicone into our group. And we’ve seen this across the laptop, iMac, and Studio. Same frame warping of footage. And it’s random. As in clearing the cache will make it disappear from one section of the footage, only to have it show up in another section.
So again, any clues to solving, or confirmations of the issues, would be helpful. Thanks all!