Your suggestion to use firewood (or other more inaccessible place) is a great one! It worked. In this video, I take the box hide game outside. She loses motivation when she’s outside, so I have to work harder to keep her in the game.
I am learning that her alerts are more subtle than my other dog. There were times that it seemed that she was being kind of spacey and not really paying attention, but as I review the video, I think she was searching and offering deliberate alerts.