It looks to me like he put SUM(Count) on the Size pill when he shouldn't have. Just remove the SUM(Count) from the Size pill, and it should be fine.
That did the trick!
Thank you very much Bill, that took me a couple of hours of clicking around and rummaging through Google & the forums to not come up with an answer.
Happy to help. I suggest spending some time watching the many on-demand videos and just tinkering with Tableau. Once you learn the "pill" and "shelf" paradigm, this will come naturally to you. Have fun playing with it. It is different from any other tool I have used, so takes some getting used to. If you try to do things the "old way," you will just get frustrated.