The GUN CODE forum has the answers to your question. You CANNOT 100% the Hunting missions just by defeating the grizzly.
You must do them manually from start to finish so skip doing the Mission Select for Hunt Missions. If you have beated the grizzly you need to start a New Game there is no other possible way to play the previous missions.
So Im sorry for anybopdy who had everything 100% except the hunting missions and they have beaten the grizzly you will have to 100% evrything else all over again........
So approach the indian and do his missions from start to finish this link should also help