The bug is: When starting a single player world with cheats enabled, and in creative. Changing your game mode with a command block to survival is possible, but changing from survival to creative isn't possible even though the text says," Your game mode has been Updated." Also, when editing the command block text appears saying, "Must be an opped player in creative mode."
I believe the game mode from survival to creative via command block should be allowed + editing command blocks, for testing purposes.
1. Start a world in creative, with cheats enabled, with super flat.
2. Place a command block with the command,"gamemode @p 1" and wire to a button.
3. Change game mode to 0 (survival) and press the button wired to the command block, Then attempt to edit the command block.