Filter Context / Transition Help

Hi Badger43 

The measure you have written is one version of a related distinct count measure.

See here for a similar example:

https://www.daxpatterns.com/related-distinct-count-excel-2013/

The important concept here is "expanded tables". Providing Expense as a filter argument actually adds the expanded Expense table as a filter, which includes columns of all tables on the 1-side of a relationship with Expense, so includes all columns of Accounts.

The result is that rows of Accounts related to the visible rows of Expense become filters, and [NoofAccounts] gives the expected result.

This is a good article on expanded tables:

https://www.sqlbi.com/articles/expanded-tables-in-dax/

Regards,

Owen