I went back to marked retrieves/fun bumpers and he wants nothing to do with it. He goes so far as to go to the back door when I open the front door and call him (we train in the front yard). You would think I beat him with a bumper the way he acts. He really acts like he's afraid of retrieving. He sits and does his obedience, so it really seems as though it's the retrieving that he's spooked about. I tried other things besides bumpers and he didn't even want to go get a hot dog inside a sock.
There has been little to no discipline involved in retrieving so far. I've told him "no" when he went to a bumper and didn't pick it up, or dropped it on the way back. But it wasn't even a very scathing "no". And there has been no physical discipline at all. Furthermore, I haven't heard him yelp as though he got hurt during a retrieve and is scared of that happening again.
So what would kill his retrieve drive so suddenly? It has been suggested that he is teething, but I haven't noticed him not chewing on toys. I realize that Avery hexa bumpers are pretty hard, but he won't get the canvas ones either.
I held off for a week with no work at all, then I threw his favorite toy in the neighbor's yard (in case he associates ours). He went and got it a couple times, so I snuck in a bumper. He got that once, then showed no interest again.
Has anyone else had a pup suddenly shut down for no apparent reason? Do I just try and be patient and let him get over it or is there something else to do?

