It's a very old bug still existing in 1.65 - suddenly an NPC ship becomes laserproof; you can hear the sound of laser hitting the target but no red dot and no damage.
I've noticed it has something to do with subentities. It happens to Wolf MkII sometimes (2 subentities) , Weelveloid Hunters occasionally (3 subentitites) and almost constantly with Hydras and Basilisks! I watched that quite close when huting down a Hydra: laser worked ok when i hit the rear side of it, but after i touched the pointy side of the ship, it became laserproof.
Laserproof ships (laser collision bugs)
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