I've noticed that if a 2nd player joins a game, the host will partly see invisible blocks of what the second player has built. Although, this only happened to me when I used the iPad 2,ios, to join a Samsung Infuse 4G,android, or the other way around. Whenever I use my LG Thrill,android, to join the Samsung Infuse 4G,android, there are no invisible blocks seen to the host. I believe that this is caused by android+ios multiplayer. ios+ios=good android+android=good, but android+ios=invisible blocks. I'm not sure if its the ios and android thing or just the devices that I am using so I'm not sure if others can reproduce this. All you have to do is get and android, join an ios device, or the other way around, make the 2nd player build a pillar and the host will see the invisible blocks. Also, FYI , if the 2nd player breaks the invisible blocks to the host,but visible to the 2nd player, the 2nd player would not get the block back. Sorry if I confused you, this is hard to explain through writing .