Unfortunately, I think we'd need to know a bit more about the data to properly answer this question. Are you able to share an anonymized sample of the data?
Unfortunately, I am under an NDA to not share the data.
So I am starting to understand how challenging a question like this is to answer for someone who can't look at the data. I have tried to ask this question in a variety of ways without success. That said, I sat down last week with Tableau Prep, which I got on Friday last week and was able to work out. The way that it shows the join with what data is included and not, matched and unmatched, really helped me help myself.
Thanks again for at least trying to help. That's what I love about this community, everyone is so willing to help even with the abstract ideas!
So glad you were able to figure it out. Be sure to mark you last response as the correct answer so people can quickly see that, in this case, Tableau Prep allowed you to correct the problem. That will also allow us to close the thread.