I've only had this happen this once, I had a half-ogre who hadn't had a point spent since lv26, he was at 50 and about to enter the void, so I thought I may as well waste them. I filled up Bow and Throwing and talked to the masters, Clarissa Shalmo told me her quest (I've done it before) and I check up near Quintara on my map for the place I have to go and its not there. I tried just going to the coordinates anyway, but its not there, so I went and talked to Clarissa again and she just told me she was looking forward to mastering the weapon. Anyone know what I should do?
If you don't make sure that she marks your map in the first conversation, you won't have it appear on the map and you won't be able to find it. I'm not sure if it's a bug or if it's intended to make you pay closer attention to the conversations, but that's the way it works. I usually get throwing master, so I've been through this several times and had it happen to me before.