First off I have never seen a Fox Red Lab. I have seen black, yellow and liver labs. I have seen light red golden retrieves and both breeds that would point or what you might call pointing, but never a Fox Red one. Now we got the elephant out of the room.
How long was she with this trainer? What did she go to be trained for and did he accomplish the goal? If it was bird work then something happened during training that has made her sulk to retrieve. Did he use an E-Collar as others have suggested? Great tool if used correctly, but one mistake at the wrong time can be real bad. I have used E-Collars, but only for obedience and I have always been very careful on timing and settings depending on the dog. He may have nicked her while picking up a bird and if she is soft natured, it may have soured on feathers all together? If she retrieved when you picked her up from the training then something happen on your watch.
Take her back to having fun and don't push her too hard on feathers. She cannot be allowed to do what she wants and stop retrieving birds all together. But, you cannot take her out of the field and hunting because is sulking to the retrieve. She may snap out of it, but she is still finding the dead bird for you!
If you table train it is the best confidence booster for a dog. They all love being at your level and you can do more with a dog on a table in a month than ground training In six. I have trained every dog flushing and pointing on a table. Best place in the world to do bird introduction work with live harnessed birds and dead bird work. You have complete control and no e-collar needed. Once your happy with their ability on the table you need to re enforce on the ground. If you have to get into force breaking to retrieve I highly suggest a table. It is the best way to do it IMHO.
I have never had a dog that like to retrieve Woodcock! My last girl GSP loved to hunt them, but hated to retrieve them. It is the only bird that she would let other dogs retrieve. Grouse is a tough bird for a pointing dog so she thought she was making a mistake it they flushed. Woodcock think they are hiding and will hold almost forever, she rarely made a mistake on woodcock. She crossed the Rainbow Bridge and is hunting with my good friend in heaven now. That's another story!