I'm going thru the same thing with SOphie. She loves her new food for the first day or so, then reruses to eat it! I've been mixing cheese, yogurt or peanut butter with her food but now I see that I've gotta stop that. Tough love is TOUGH!
This morning I set her food before her and she didn't eat. Hopefully she will eat when she gets hungry. This means no treats while I'm training her
Maybe I should delay the training until her eating her food resumes.