Invisible war wasp group in the map "Drip Moat - UNIT4_C1"

[PixellBits]

when i first entered that room, the group of ice war wasps coming towards you was invisible without any collision, although the sound of them flying still played normally. after revisiting that place now, the sound of them flying doesnt even play anymore, but im not sure if they only spawn the first time you enter that room