Hi Colin
We have had vizslas in our lives for many years. The anxiousness at being left outside shops and the over-the-top greeting is not unusual - they are very attached to their people! You are lucky that she copes with the 10 hours a day by herself without barking or other anxiety behaviours. Many struggle with that.
I agree with the vet check being the first step. One of our girls went from being a sociable puppy to a reactive nipper at the age of about 1 year. It turned out that she had hip dysplasia and was understandably very nervous of any dogs near her hips or just playing too boisterously.
Kira Ryle at caninecode.com.au gets a good wrap as a behaviourist. I know she has worked with a couple of vizslas and is in the Bayside area.
Good luck - they are beautiful quirky souls.