In Zafaria, in Queen Elissa's tomb, right at the end it asks you to speak to her on her throne, however she never appears and you cannot complete the quest. I looked in my questbook and the next storyline quest appeared, to talk to someone in the Baobob Crown, but still thought I would post here. I saw someone posted the same glitch in 2013, so I take it that it's been around for ages.