NPC #30298 (possibly named "Invisible Stalker Float Uninteractible Largeaoi") doesn't exist. It may have been removed from the game.
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Invisible Stalker (Float, Uninteractible, LargeAOI) - Live
Invisible Stalker (Float, Uninteractible, LargeAOI) - PTR
Invisible Stalker (Float, Uninteractible, LargeAOI) - PTR 2
Invisible Stalker (Float, Uninteractible, LargeAOI) - Beta
Invisible Stalker (Float, Uninteractible, LargeAOI) - Wrath of the Lich King
Invisible Stalker (Float, Uninteractible, LargeAOI) - Cataclysm