Val is right - target panic is mental. I think you did the right thing by switching releases. I also suffered the same thing and solved it the same way as you except I went to a thumb type release. I am now back to my Scott trigger release with no problems.
Another thing to do is to stand about 3-4 feet from your target block, draw aim at the center of the block, close your eyes and without moving the bow focus solely on the release. This will have you releasing your arrow without your brain telling you when you are ''on target''! This is what I do when I occasionally start jerking the trigger.