Is it intended for the boxes to shift slightly after a perspective shift? I found that sometimes a box which was on a button would suddenly be half off the button after a switch and I can't move it back due to being snapped to grid, but the box is no longer snapped to grid. Would mean I had to restart the level.
Managed to beat all the levels though, the detached movement of your grabbed box was a bit trippy but was interesting when I started actually planning it.