I created a tunnelers dream super flat and started messing with scaffold and towered up to height limit, I was just messing around to see how far it would let me go. So I went out in the 4 cardinal directions until it stopped. (This is another issue but it doesn't place and fall like normal, it just brings up the height limit message)

if you then go out onto one of those extensions like 2 or 3 blocks and then try to place one to the side it will remove the one you're standing on (without giving back the item) and place a new one in the direction you're going. This then disconnects it from the tower but you can keep doing this for quite a while, If you try to do it too fast it removes itself and you still don't drop the item.