Same issue for me. Like someone else said, I also noticed that Sync Shot wouldn't work a few times either.
Never could resolve it, just played without until eventually it would (perhaps after being hunted?)
Another huge patch, and this bug still persists!
So frustrating.
Soooo frustrating.
And no, all the snake-oil remedy don't always work to fix the issue, and relaunching the whole game, while knee deep in a compound, is NOT the final solution. Come on Ubisoft, please... look into this bug! Even if its just to come up with a command or key we can use to 'reset the bustedness' somehow. Doesn't need to be elegant, just something that lets us keep playing where we are.
Yea it happened to me today after upgrading to the emp and explosive drone. After getting out of a helicopter and blowing a few things up, it would no longer work.