I noticed an odd thing a couple times while making a large outdoor map, so I decided to test it, and it occurs every time at the 20% zoom, but not at any other. If you have a token or object that extends beyond the bounds of your map, it extends the view out to the edge of that token/object, as can be seen in the screenshot below: This is at 10%: And this is at 30%: I have checked it all the way up to max zoom, and it only occurs at the 20% mark...