Commands become a chat message

When you type the command "/kill @e[type=Sheep,name=Spawn-Snow-Golem]", it then goes onto the chat, the whole command. (See pictures for what I mean.) Like if I did it, it would say: "<JojoTheMAN21> /kill @e[type=Sheep,name=Spawn-Snow-Golem]".

The weird part about it is you can do any command. All you have to do is press the up arrow or re-paste and then delete until the / is left. Then type away! /help, /setblock, /summon, /me, all of the commands are then broken. You can even type your own command, like /sit or something.