sounds like a classic case of target panic. ive been there done that. if you're concerned about curing the problem then there are steps you can take to do so...however you said that you switched to a 3d target and were fine, so don't sweat it. spot shooting is pretty much a thing of the past unless you're shooting and indoor 5 spot round. if you need to correct the target panic you can do the following. and remember be patient, you're not going to correct it overnight.

1. temporarily switch to a pressure (triggerless) release like a "staneslosky".

2. stand 10 yards from your shooting bail and draw your bow back get it somewhere on the bail then close your eyes and finish your shot. this will get you use to "feeling" the shot which is what you should do anyway.

3. repeat step 2 only keep your eyes open this time.

4. when you feel comfortable enough to move back to shooting spots start out @ 20 yds and use a 40 yd or a 60 yrd target (bigger spot). gradually work your way back to the appropriate target for the correct yardage.

and finally....typically the longer the yardage you're shooting the worse the "target panic". you have to mentally condition yourself into knowing that fundamentally there is NO difference between a 20 yard shot and a 40 yard shot. after you've corrected your "target panic", during your practice sessions...don't practice at 20 yrds. when im shooting 3d steady i don't practice at 20 yds. i typically will practice at 40 yds or farther. it makes the shorter shots seem simpler and builds your confidence.