1432274 - A database error occured. The database error text is: The MDX query SELECT... failed to execute with the error Specify a value for variable WIS 10901

In BEx, when having a mandatory variable set on a characteristic and an optional variable set on the same characteristic in a Structure, getting an MDX error in Web Intelligence report based on a universe using the BEx query when trying to view LOV:
"A database error occured. The database error text is: The MDX query SELECT... failed to execute with the error Specify a value for variable {...}. (WIS 10901)"

• BusinessObjects Enterprise 3.1 SP2 or later
• SAP Business Warehouse v7.x

BEx structure, Webi MDX error, optional and mandatory filter BEx , KBA , BI-RA-WBI , Web Intelligence , Problem