There are a few bugs that are significantly crippling my ability to play the game. I can't find a specific place to report bugs other than a couple of forums.
First of all, the diamond duplication glitch. Diamond is rare for a reason - it's one of the most valuable elements of the game and is used to forge the best equipment. Being able to duplicate with almost no effort defeats the purpose of the game. When people join your world and start doing this, it interferes with everything and instantly makes them better and more able players than you, no matter how long you've been playing or how many resources you have. I'm sure it's been reported before, but it won't hurt to do it again. I think the same glitch is present in the PC version as well, so maybe I could report this as a PC glitch and mention that it is also on other platforms.
Another thing that I don't like is the way the invitation only option works. Even with "Allow friends of friends" turned off, if someone in my game has a friend that is also on my friends list, they can invite them to the game without my consent. If I set the game to invite only, I should be the only one capable of inviting someone. Does this intentionally work this way or is this a bug? If nothing else, I'd at least like to make a suggestion that this be changed.