So I encountered a potential bug. I was killing the void as quickly as I could to progress to higher levels of the rift, since the lower ones were not grind worthy any more. I killed the level two rift, and the level three stage rolled out, but there was no level three void, and there was a blank untargetable space at the beginning of the level. I cleared the level just to see what would happen, and I got the level five chest.
Great game!
For those having trouble moving the pieces, try finding corners that can serve as fulcrums. You can drop 3-4 pieces into place in one swing.