What version of BI4 (SP and patch) are you using? - BI 4.0 SP4
When you say the report "hangs" does this mean Analysis OLAP becomes unresponsive and you have to close its tab/window and start again? - OLAP unresponsive and yes I need to close tab and window.
Does the problem occur when you try to open the member selector to pick values? - YES
What happens if instead you directly enter a known key value for Material. Does the query return results correctly? No issues when enter material value directly
Thanks,
Raj