I gave the "treat-retreat" thing a try, and it did not seem to have the desired effect. She generally won't stay in the same room as me if no one else is there, so when we tried this my wife was nearby. Pearl was standing by herself and just looked at me when I threw a treat, it was not until I threw 3 that she decided to go and see what I was throwing. She ate those and just stood where they had landed to see what would happen next, then because I was looking at her she thought better of it all and went and hid behind my wife's legs.
Anyway, on to the BAT exercise and see if that goes anywhere.