IWD: problem in Dorn's Deep

[Henry Lockwood]

Spoiler space...

OK, I only recently got IWD, and I'm playing through quite happily.
I'm in Dorn's Deep, and my party isn't really having any difficulty with the
opponents we're encountering. I've met Saablic Tan, the Red Wizard who's
been polymorphed into an Umber Hulk, and he's asked me to kill the Neo-Orog
chieftain. I've done so, and got the badge, but when I go back to talk to
Saablic he doesn't recognise that I've got it. Is this a bug?
If so, I'd be grateful if someone could suggest either a workaround or a
fix.