By far the most common problems that I see in my gundog training classes are owners struggling with dogs either not wanting to go pick up a retrieving item or, funnily enough, not want to bring it back.
Bearing in mind that the dog is a social predator and has a “what’s in it for me” philosophy, along with pretty much the rest of the animal kingdom, training them to retrieve something has to be motivating for them.
It could be that they think it’s fun or that they want to please you, however it’s not always the case… why, for example, should your dog run out and pick up a toy when there’s a flock of birds at the other end of the field that it can go and chase? Why should it put the item in your hand when there’s the most amazing smell six feet away from you that needs to be investigated and licked first?
And as for a gundog training dummy! Really? You expect your dog to gently pick up a canvas bag of sand, bring it back and put it in your hand… with nothing in it for the dog?