I finally found a solution. Go into the menyoostuff folder that you placed inside GTA V. Open the file named menyooConfig inside the folder, press Ctrl+F and type stop_animation_key in the search box. Normally it says 74, which corresponds to the 'J' key. Change it to 0 (this removes the command from the keys) and you will have solved this problem. Thanks to everyone who helped. (By the way, if you try to change it without entering the game after installing menyoo, you won't be able to find stop_animation_key when you search, at least I couldn't find it. Enter the game once, activate menyoo, then exit the game and do what I said.)