Agent W does not appear

I don't know what you're talking about but this isn't a glitch lol. Once you get your watermelon, just fall onto a hogou or whatever its called. Once you get 5 watermelons, go to the agent HQ. You go to the HQ by talking to Agent E (the girl) and clicking take me to the HQ or w/e (first option). There, you will see Agent W and you can complete the quest and get a pink tube thing in your class.

I think Isaac is basically saying "this was here in KMS, and GMS failed to add it".