KB289456: How to query the elements for a prompt answer list from the last dataset instead of data warehouse in a document based on two or more datasets in MicroStrategy Web 11.x

This is a known behavior that when two reports based on Intelligent Cubes are used in a Report Services document, attribute element list prompts hit the warehouse instead of using the available elements from the cube, as showed in below technical note.
KB31987: A Report Services document using two or more prompted reports based on Intelligent Cubes queries the data warehouse to generate element list prompts instead of reading from the Intelligent Cube in MicroStrategy 9.0.x
In Strategy Web, there is a option in sys_defaults.xml to change this default behavior.  
Default file path is C:\Program Files (x86)\Strategy\Web ASPx\WEB-INF\xml\sys_defaults.xml. And user can set value to be 'v="1"' in below section:

<pr des="Whether to use last dataSource instead of all dataSources to get elements" n="useLastDataSourceToGetElements" scp="system" v="0" dt="boolean"/>

After modifying the sys_defaults.xml file, there is a need to re-start the IIS and run the WebAdmin page (http://<serverName>/Strategy/asp/Admin.aspx) to rebuild the necessary files.
After the value is set to 1, the element prompt will use the answer list from last dataset instead of warehouse.