I attempted leaving the breach value as is and lowering the cooldown to check many results - no breaches.
I attempted upping the breach value to 8 (per fire beam) and then 10 (per breach bomb). I tried this with both standard cooldown and lowered cooldown - no breaches.
I attempted using both beams that already had breach values in the original game and ones that didnt. This makes no difference.
I even attempting changing the weapon type of the Hull Beam to Laser just to see what would happen. This does not make the game happy.

Anyways, it isn't ruining my life or anything, but it does kind of arbitrarily limit what beam weapons can do. They cause fire just fine, thats for sure!
Thanks, and awesome game!