Okay, the dialogue about Werei sounds like it should actually be related to the quest, so that should be where you're given the option to cancel it? Gumbah has a lot attached to him, but that doesn't seem like random unrelated chatter.

So yeah, if you're not getting that option, that sounds like something's broken in a dumb way. I know every time I tried to talk to Shantotto with the staff quest active, she'd ask me if I wanted to give up before I could get any mission-related dialogue.

Funny how stuff that hasn't needed to be touched in, like, twelve years or so just up and breaks out of nowhere sometimes.