Looks like AI try to predict cannon/beam projectile path without any attention to increased projectile speed. It predicts too early. And can't ever hit enemy.

Projectile is faster than AI thinks. That's a problem. You can test it out. I tested it multiple times and will do it again.

You can see at picture, that wrong-predicted angle is equals to 2 right-predicted angle. I think it's because cannon/beam weapon have double speed of projectile.

I might be wrong, but you should test it.
Cannon/beam weapon should at least hit 10% times 4k mass target at 4km range.