I had the same problem and a guy from LG tech support fiqured out it was the Lookout App. Disable the app, and then restart phone. Steps Below.
Hey there! Thanks for posting this! I'm sure it'll be a big help to others with the same issue!
OK. Bad news... When I restored my my phone the mobile network disconnected and has not been able to connect since. Very frustrating.
Removing the battery after the steps enabled me to connect to the mobile network.