My gorgeous 7 month old puppy is an absolute delight and training so far has been so easy. She has always been brilliant on the recall, with a whistle and without, but all of a sudden she does not come back when other dogs are around - not until she feels like it. It's like she has gone deaf (and defiant) Has anyone else experienced this? Is it an age thing? I would love some advice as I feel like all my hard work is going down the drain!!!