I had this problem and it is on the LG Flex. Inside the Settings back menus, there is a feature under the DISPLAY group called HOME SCREEN that you must uncheck that says that the home screen can never rotate. Also there is a button that must be turned on that will then light up as active on the main (first) primary settings screen that has brightness, bluetooth, sound, WiFi, and other options. This primary options screen is the one at the top that is visible when you run your finger from the top to the bottom on your phone.