Hello fellow LG G3 owners,
After much frustration, I am pleased to announce that I figured out how to unlock wifi "Mobile Hotspot" tethering without root.
1) enable debugging in developer options on your phone
2) set up android SDK and ADB on ...
One of my co-workers suggested that it may be caused by moisture inside the phone. I set it in the sun for a while, and the problem seems to have gone away.