HELP ! Game Difficulty reset and locked

The difficulty reset itself and is locked in peaceful mode. Does anyone know how to change that?

EDIT: I added another world and set the game mode to normal. As a result I can now reset the game mode in the Main World to normal. However, when I switch between worlds, the new world remains in normal mode but the Main World resets itself to peaceful mode. - I’m a bit lost here

http://pastebin.com/embed_iframe/498BmwC9

An issue was reported on the github issue tracker that is likely the same problem that you’re having. Watch the issue to find out when a fix is available.