I agree with all the other guys here have said. I have a 7 month old lab from great lines, and the trainer was having a heck of a time getting him to go into thick cover to retrieve anything. Once he shot live birds down over him, it was game on. The comment made about "clicking" while on live hunts is very true.
Also, remember all dogs learn at their own pace. While your dog might not come from proven lines with hunt test results, it doesn't mean that the lineage isn't capable. If she's going out, retrieving with enthusiasm and isn't afraid of the gun, then you have a dog that will work long term IMO. Every dog has its quirks, just be patient and see. Also, if your dog has already been force fetched, but is still playing with the birds on land, then the trainer probably needs to go back to the force fetch table and tighten that up. If it's been done properly then the dog should be bringing the bird back to heel every time without fail.
Patience, practice and exercise. Your dog will be fine. We all have high expectations of our dogs, and sometimes it can be overwhelmingly frustrating when they don't progress as fast as we'd like. I always tell my buddies that my new dog is like the fat kid in gym class or he's riding the short bus to school. He's a bit dense. Now that I know that, I can lower my expectations here early in the dogs life and give him the patience and understanding that he needs to succeed. Spend a lot of time with your pup and all will be good.