when I looked at my network mode. I see mine is set as "manual". I originally unlock my phone with the thread posted in the the main page (http://forum.xda-developers.com/show....php?t=2176720) and I do believe I also use the same setting there to lock to LTE as well. not sure if that make any difference.
Yes been running beta 2 with Agni 4.2.1 kernel for over a week. rebooted once on fist day, Also today audio went out after installing Viper4Android and had to reboot.
But all the 4.4.2 and S5 features work very nice.
My install: in installation I installed with out tracks and stock kernel let fir for about 10 minutes
then flashed SU and Agni Kernel.
Shutting off all sync I had 41% battery left after 15 hours with 3.23 hours of on screen.
Also installed in Xposed DVFS Disabler and Battery calibrator.
in settings >wifi >advance >un-ticked always allow scanning.
No need to flash modem, note it does now have the ATT model number not tmobile.