Since upgrading to Sierra I've noticed that sometimes when I swipe between spaces the background image moves left or right as I swipe along with whatever icons I have on my desktop and whatever (lets say) open finder windows I have. Other times the background remains static but everything else moves left or right as I swipe.
I have the same (default) bg image for all spaces.
I have also noticed that the behavior seems to remembered by the space I am moving to/from. For instance, right now I have 2 full screen spaces and then 4 "desktop" spaces and then 2 more full screen spaces. And if I swipe into or out of the desktop 4 space then the bg remains static, but swiping to any other space, the background moves.
I realize this is not a big deal, but it's annoying... thoughts?