Simple, unimportant bug.

If you select Hardcore as your game type, then go to More World Options, as expected, the "Cheats" and "Bonus Chest" options are blacked out, and you can't even click them. However, changing the world type to "Buffet", then clicking "Customize", then backing out, allows you to click the "Cheats" and "Bonus Chest" options again. Thankfully, you can't actually change the settings, but they still appear as normal buttons, and are infact clickable. They remain that way until you change the game type off of Hardcore, and they become unclickable again once you swap the gamemode back to Hardcore.