phone not registered yet FIX
A simple and easy fix. Replace the sim card from your local ATT store
Back up whatever media files etc you have on your phone.
Do a factory reset
Now your phone should update properly.
This should work for all variants.
This is due to leaving in the sim card while using the flashtool. It messes the sim cards registration with the phone up.
As a reminder whenever doing a reset with flashtool remove sim card or this will happen.
AT&T LG G2 D800--D80020c-rooted -wrapped in Ballistic SG MAXX case.