Can you post a packaged workbook demonstrating this? I understand the problem, but don't know how to guide you to getting what you want without playing with the workbook a bit. Would it help if the blank values showed up as zeroes instead of blank? If so, something like the calculated field below may work:
I think I figured this out today. I had Null values in some measures for items, from conditional (IF) statements where I was returning a Value if positive, but nothing if negative. Adding an "ELSE 0" to those statements solved the problem. What was quirky was that the Total of the Columns was correct, but there were no values when a row had a value that was NULL.
Great, best of luck.
...from ALB's mobile