My Celtic is not very food motived, it drives me crazy. He likes some food and some like Peanut Butter, he absolutely hates. But I need to tell you a story.
Last week I took Celtic to a new conformation class. I brought his favorite treat, one he normal works his heart out for. I was nervous, new place and I am not comfortable with conformation training. Celtic was not himself , he wanted to sniff girls, did not pay attetion to me and would not even look at me. He would not even sniff the treats, plain did not care. As a result, I got more and more tense and mad and pleading and tried to control him more and more and he completely melted down. It was not pretty.
Now Celtic has trained all his life in obedience and agility and he has even showed in conformation. He can be a bit difficult but I had never seen him act this way before. No treat in the world would make him pay attention or any amount of pleading, begging, coaxing or manipulation. I was on the verge of tears. I really need him to learn this and he is not helping!
At about 20 minutes in , the instructor asked if she could take him. Same treats, same leash. She stepped back 3 ft turned, talked to him, turned, gave him a treat and he was bouncing, eating, and so happy. She turned came back to me and said quote "he says I am fun , YOU are not fun" She said my body language is telling him, I am tense, upset and unhappy. He doesn't know why but it has something to do with the situation. The way he is acting is his way of dealing with the stress he is feeling. It will never change until I change my mind set. Relax and let him learn and not try to force him to be perfect right from the beginning.
Let me tell you, what she said was like a bucket of cold water being dumped on my head. I stepped back took a short break, let out a few breathes and let it go. When or turn came up again, Celtic was much better. We were not showing well but atleast he was trying, paying attention and eating. We went to agility class 30 minutes at a different school and it was like a switch was flipped. Same treats and he was gobbling them down, totally intune and happy. It just reaffirmed it was my issue not his, I was happy, confident and relaxed so was he.
We went back to the same conformation class yesterday. I went in with the attitude that I was going to have fun with my dog, listen to my instructor and be happy with any effort he gave me and make a mental note of what we needed to work on for next week. Wouldn't you know, Celtic was a rockstar. He did everything I asked, the best I have never seen him. I need to work on a lot of things with myself but wow!
I guess the point is what we see when training our dogs is feedback. She is not motivated, it maybe the food, it may not be. That fact she worked for your instructor in the same time span makes me think she is feeling some of your stress. Your frustration. It is just a suggestion. Sit back and think about how you feel when you are in class. Are you on edge, frustrated , happy sad, what? When she does what you want how do you feel? Wow you are the best or finally you did something right. Shelties are very sensitive to our state of mind , more than we often realized.
I forget how old Cleo is but remember dog training is a journey. It never ends and we are always teaching and improving on what they know even when a 6 week class is done. It will come, relax and enjoy your dog.

I really needed that reminder this week myself.