Light Tracking Missiles won't fire?

https://preview.redd.it/senhyi6lz9hf1.png?width=1323&format=png&auto=webp&s=d961575f976d94863032dfde887b79570af1cafa

I built my first missile-ship, I loaded it with Heavy Swarm Missiles, it worked great. I refilled it with light guided missiles, now it won't fire.

I've tried setting the missile launchers to primary weapon, secondry weapon, another slot in the secondary weapon system.

Weird thing is, I had a couple of Guided missiles that I must have picked up somewhere. I switched to those, they fired perfectly.

But the light guided missiles won't shoot.

What's the deal? Do these require torpedo launchers or something? But in that case, why would it let me even select them as a useable ammo type?