After a long time arguing with my own, I found out that the first batch of LG G3 sent to Indonesia, the International version, had their LTE setting disabled. Thank God, there is XDA forum. Also thank God, I have rooted my phone.
The solution is simple if you had rooted your phone. This will require a rooted file explorer like ES File explorer.
- Make sure that your root setting enabled in the explorer.
- Go to \system\app.
- There will be a folder named LteConfigs. You can either delete of move the whole folder somewhere else. I personally remove the whole folder.
- Restart the phone.
For note, I also tried to dial 3845#*855# and setting through that. But the setting is gone when the phone restarted. I also tried editing using prop editor, but somehow the setting also reset when you restart your phone. So, this is considered as a permanent solution for me.