Small Black Bar Appearing on Side of Video After Rendering

I have a video that is a combination of video files, stills, and time-lapses created with the image sequence function at import. Everything has been scaled manually to fit the frame since they are all different sizes, but each time I render, all the footage shifts slightly to the left leaving a gap between them and the right side of the frame. They're being transformed to be less wide (rather than being shifted), but when I rest position and scale to try again, it still happens when I scale the image back down.  Interestingly, if I rest opacity (which has never been changed) or the Lumetri color (which has been used for clips, but not stills), the image snaps back to the full frame width, only when I render again, it resets with that narrow black bar on the edge.