I'd agree with you Clare. One problem might be that she's lost her confidence/drive on them, maybe cos you've unintentionally done a bit too much retrieving with her. The looking at you wagging thing suggests she's not sure what to do, which is what my cocker will do if you keep on chucking the same bird out over and over. It's like she's saying "I've brought it back all these times and you keep chucking it, so that's obviously not what you want, and now I don't know what to do?!"
Having said that, are these freshly killed birds she's having the problems with, or cold'uns? Does she run str