Further, I found that it's not just measures in/out of view affecting this. If I pull a dimension from "Commission Payable" into view, the total "BulkQuantity" increases to the unexpected amount. The value is spread among the rows. This might be a clue and I'm thinking about it now.
Look at the relationships set up among these data sources.
I'm guessing you are blending on more (or less) than you think you are.
But guess is all I can do. On the surface, what you are doing should work smoothly. I have sheets all over the place that pull measures from secondary sources without problem.
I would need to see your workbook to do something more than guess. But looking at relationships (and what you have clicked on for blending) is where I would look first.
I was blending on InvoiceNumber for one, but dealer name and MY(InvoiceDate) for the other.
I would say that those blends have a very different granularity.
Switching them to both be DealerName and MY(InvoiceDate), seems to solve the problem.
So it seems to pull in the BulkQuantity beside every InvoiceNumber, regardless of whether the invoice numbers are in view, and then it sums that up. I think the BulkQuantity must be repeated for all invoices that have a matching DealerName and MY(InvoiceDate).
Not intuitive, yet understandable