
As Polly says - difficult to say without seeing what's happening.
Posession of an article is something that can be picked up on very early when we do our puppy character assessments at 7 weeks - we can then tell the new owners if the pup has any little quirks like this (yes - you can see this very early on), so they can organise their training to suit.
I would't even try to do any retrieves for a while, and certainly don't play tug of war - ever - you've worked this out yourself! You need consolidate a good basic recall,, which it sounds as if you do, but keep working on it that she comes right into you - almost up your nose!!
Then go back to getting him to hold it in the 'sit' in front of you in the front room. Personally, when she's done this quietly, I would give a little treat in exchange for the article, but some would disagree. At this stage, banish completely all of her own toys from the floor - it confuses the dog's mind. She needs to know that the dummy is yours, and be focussed on you. She's outgrown toys, in my reckoning.
Please tell us where you are, and we can advise of suitable trainers in your area. You need a trainer who is quiet and not going to wind the dog up - unfortunately not all trainers come into this catagory!
Jo and the Casblaidd Flatcoats