Thats strange, I have my phone in CDMA Only Mode and everything is fine. I have 1x wrking and 4g is off.
Im not really sure what the fix would be but im sure someone here will be able to help you. But until then you can use the LTE shortcut method, I know it sux that 4g comes back on after making/receiving a phone call and you have to shut it off again but it should hold you over until someone can help you with a better fix. If you dnt knw about the shortcut, just dwnload "Anycut' from the market (
Here ya go) once you have it installed create a shortcut and youll see the Anycut option, click it and go to Activity, scroll down until you see "LTE Functionality Test" click it, name the short cut what you want then click ok. When your shortcut is made and you click on it youll see at the top, "Turn ON" and "Turn OFF" thats to turn 4g on/off, I wouldnt mess with anything else on that screen unless you knw what your doing. Hope this helps ya.