and my guildy didn't encounter any problem with Morrok at all, if it isn't a bug like what they claim, they should at least give us a hint what we're missing.
I don't think you're missing anything. I've noticed that the quests in this new zone just randomly bug for (seemingly) no reason. I had an issue with an NPC not appearing in a side quest, so I skipped it, but other people had found the NPC with no problems. About 3 hours or less after I finished some main quests in Syrbal, players that came after me suddenly couldn't complete those quests anymore.
That being said, since they weren't bugged from the start, it's likely that the weekly maintenance will fix those quests (at least for a short time). So you might not have to wait for a patch for a fix, but it is definitely annoying.