Join the club buddy! I struggled with this my first couple years a field. I could shoot lights out on targets all day long. But when the time came to shoot an animal, all bets were off. Between my first two seasons a field, I missed 11 deer, all of them were perfect left to right, but every single miss went barely high over the back. Shots ranged anywhere from 8 to 20 yards...
I threw my bows out of trees, got up from my ground blind and walked out with hours of huntable light left, cursed myself to sleep, you name it... I was fed up. I couldn't understand it.
Then the light bulb went off in my second season when I put my first deer on the ground. I picked that tuft of hair out, and my arrow hit right where I was looking. I've had some random misses since, but my accuracy on game animals is very close to my target shooting now because I've gotten in the habit to shoot at live game just like I shoot at targets. Pick That Spot!
Fred Asbell made sense of my syndrom when he said, "the human eye is attracted to defined lines and edges. If you don't conciously pick a spot in the vitals, and you are simply staring at the animal as a whole, you will miss high. The reason you will miss high most times is that the most defined line on a game animal is their back line."
With the minor dropping motion of a game animal as your arrow is in flight, accompanied by the fact that your subconcious has just picked, aimed, and shot at the back line will equal a shot missing high most times.
It took me some crushing misses on still to this day would be my best bucks yet, and countless doe from the ground with no blind which would have made for some great hunting success stories around the camp fire, but it can be overcome with a little bit of composure in the woods. The tough part, is that with every miss, the anxiety of the next shot gets more intense and the desire to make the shot grows more each time. This just adds more pressure to the situation that further inhibits our shooting ability in the field.
Step one getting over this, is to forget about all your previous misses. Just like any sport, if you dwell on your poor performances of the past, it will directly affect your performance today. Put them behind you, and make the next one count. Stop thinking, pick the spot on the game animal the minute it comes into the hunting scenario, do not take your eyes off the spot no matter how long it takes for the animal to present a shot, then make the shot. After you do this on a couple game animals, it will become natural to find that spot right when you are ready to shoot.
Stick with it. It's a journey, and I wouldn't trade any clean miss I've had with my recurve for a kill with another more advanced weapon.
Good luck.