So apparently GBU-12 is a guided bomb in real life and in the game you can't target them ...
- Legacy ID
- No Bug
- Unable To Reproduce
You need someone to point a laser designator at a target and then turn on the laser before you can get a lock with an LGB. It's not clear from the description if you have followed those steps. Modern planes can 'self designate' through the use of a target designation pod or built in hardware.