Parallax background images seem to rescale and reposition upon scroll on all my pages—not like it’s intended to do, but there’s a sudden jump in scale and position before the smooth parallax effect begins. Sometimes the jump happens on load, but most of the time it happens as you start to scroll.
As an example, here is a page header upon loading:
And here it is upon scrolling:
The image jumps to that new position before the parallax effect starts.