I have two data sources with different level of granularity (Date Source 1: Purchases & Data Source 2: Payments). I am blending the two data sources based on month, product type & few other attributes. I noticed that the value for the total SUM(purchases) changes as I filter on Product Type. There will always be data in Data Source 1 for ALL Product Types, but there may not be a corresponding value in Data Source 2. Currently, Tableau is reducing the number of total purchases if there is no value for Product Type in Data Source 2. I attached a sample example.
Could you please suggest if there is a work around for this?
Do you get the same behavior when you have established a relationship only using Product Type with Purchase Data source as Primary.
It is hard to tell without knowing the data and relationships in your case.