This appears to be a bug, but before I put it into the bug reports, I found a resolution for you. Most likely, you have gone to see Martin, but haven't killed the gnoll leader (check the cave behind the Gnoll huts in Tri-Top hill. I checked repeatedly before then, and I always got the broken dialogue link. After I finished off the gnolls, the dialogue worked like a charm and I got the next part of that quest.
Ill have to try that next play thru have moved back to the regular game, but you might want to add in to Martins dialog saying like you must finish off the threat of the gnolls or something along that line