I have tried for 2 hours and could not find any good solution for these. @@
It seems that the customer filter always affects the result of data-blending.
Then the records of primary data source without corresponding customer data in secondary data source will not display on the view.
[A]: Using parameter instead of customer filter, and another calculated field to calculate customer unit by parameter value.
parameter =ALL : cust 1 units *1 + cust 2 units *1
parameter =cust1 : cust 1 units *1 + cust 2 unit * 0
[B]: Insert some dummy data during data preparation step. (by R or python/panda)
Add dummy records for every [cate prod], [customer] with [customer unit] = 0
Using the same workbook without any modification.
Then the customer filter will not affect data-blending result.
Thank you for trying, unfortunately I am not sure how I would add dummy data, I have over 3,000 customers which would make the data too large.
I have tried your suggestion [A] but with no success.