On your end? Do you mean your shooting a target that is a sub grid of the actual weapon?
if so then you may need to enable sub-grid damage in the world settings before loading your world.
Edit:add another possible cause- you may have friendly missile damage turned off

i was shooting an enemy grid, and it wouldn't do damage. has been a few days so next time i'm on SE i'll try it again

I have the same issue, it seems related to the shield mod : when the shield is down, the missiles does not get any damage. However, when the shield is up, it damages the shield and then when the shield overloads it destroys the ship.

I get another problem with the Swarmer which does not dissipate heat so it never shoots again (the block's log shows "Infinity", it might be a division by zero).

I have tested it, and it does damage, just a really small amount of damage for what torpedos are. like, they'll penetrate a layer of large heavy or small with exactly the same level of damage. I'm slightly disappointed with this

Ive found that uninstalling concealment helps if youre using Torch DS