I flashed endless zips trying to fix my LTE on Cyanogenmod 11. Nothing worked until now. So for those STILL having issues here's a Modified APN ZIP. I flashed my GNex back to stock 4.3, then navigated to /system/etc/ and copied the original apns-conf file that came with the stock ROM and saved it to my PC. Then I downloaded the Ting APN Android 4.3 version 3.zip file (Google) and replaced that apns-conf with the stock version I saved earlier. I re-zipped it as 'Ting_APNs_Android_4.4 (02-28-14).zip'. I rebooted my phone to Recovery Mode (TWRP) and did a factory reset (REQUIRED). Then I flashed my 3 ZIP files; CM11(ROM), GAPPs 4.4, and my own Ting_APNs_Android_4.4 (02-28-14).zip. Reboot and setup your device really quick. That's it! If LTE doesn't show up right away disable Wi-Fi if enabled, navigate to Settings>Mobile Networks (under Wireless & Networks) and make sure your mobile Data Connection is enabled and LTE is selected then navigate to Settings>About Phone>Sprint System Updates and click Update Profile and Update PRL. Thanks to the original creator of this file.
LTE/MMS APN Fix Android 4.4 (Kit Kat)