dog classes are training in a false environment in the same way the mutt will respond in the garden and in classes but will not respond in a field and are not worth a jot to ya,
your dog has show his drive is turned on entering a field, no question, not in the garden or anywhere else so that is where you need control, do all your bonding and training in fields anything else is a waste of time ,
you need to be able to work with the mutts drive stimulated mind not in a different mindset,he learns quicker in drive than any other state of mind, you control his drive you control the dog simple