Just keep using eagle eye, even after pressing RB to track.
Hunting is quite tricky in this game. It's not like FC Primal or other games, it takes patience and planning, but above all practise. You need to follow the animal, watching it for a while, then choose the moment when you want to take your shot. If you do it when there's loads of other animals around or in an area where they can hide easily then you will have these problems. I've not lost one injured animal yet so it's more than possible.