Well, I just learned something new about this nosework business. Moss was sometimes indicating the wrong box. (He has learned to do a nice sit when he finds the hide.) I was frustrated because I couldn’t understand why he was doing that.
I posed the question in a Facebook group and discovered what was going on. There is a thing called “fringing” which means he has caught the scent, but not the source. He’s not wrong, he’s just not completely right. So the solution is to praise him anyway, but reward on top of the correct box.
Sure enough, after one wrong alert, the rest were all spot on no matter where I put the box.