Digging through my code a bit, there are three switch checks on the Khazeem fight that you have to get through to get the Mahir ending: GoodEndScene, HaremSlutMode, and EverWoreCharm. Not sure on GoodEndScene, EverWoreCharm is what it sounds like. But HaremSlutMode is probably the issue. It ONLY gets set if you get to Khazeems's HQ via the secret stairs in the Host Club. If you get there any other way, that switch won't be set and you won't see the scene.
So you have to get the charm, wear it at least once, lose to mobs a LITTLE so Mezz will be willing to go in the host club (and have the outfit), but not maxed out (or you'll just get auto-taken to Khazeems' HQ before you can get to the host club), work your way through the club, and take the secret passage to Khazeem's HQ, then WIN. That should get you the scene. I'll talk to OpenFireplace about potentially updating the guides a little.
Oh, and no, no discord, just the forums here.