pup retrieving question.

i recently purchased a pup that was 4 months old and have been working him and have run into something i haven't seen before.

when i throw a bumper he has tons of retrieving desire and hits his marks very well. on the retrieve, though, he does not want to bring it back. i have tried running away, flipping another bumper by me, making tons of noise, etc. he brings it back, but not to me. he wants it. i have seen that before and have been able to fix it by putting the pup on a check cord and bringing them back. with this guy, though, if i put him on a check cord and tug him back while saying here, he immediately drops his bumper and runs to me. i tell him no and to go get it, which he does and then tries to run away from me. once he hits the end of the check cord and i call him here he starts bucking around, but holds the bumper. he wants the bumper in his mouth, but just doesn't want to bring it to me. what kinds of things can i try to get him to come to me. i ignore him if he doesn't and pet him and make a big deal if he does. he is getting close to 6 months old now, so i will be able to start teaching hold pretty quickly. should i just wait until then?

thanks in advance
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