KB258667: A RunningSum metric shows NULL values on a Report Services document in MicroStrategy Secure Analytics Platform 10.x

SYMPTOM
In Strategy Secure Analytics Platform 10.x, a RunningSum metric shows NULL values in a Report Services document, but shows correct value on reports.
STEPS TO REPRODUCE
The following steps are based on the Strategy Tutorial project: 
 

• Create a metric called M1 with definition below:
  M1: RunningSum<BreakBy=(Brand), SortBy=([Year])>(Revenue)
  

•  Create a report called R1 with attribute Year in row and metrics Revenue and M1 in column; also place M1’s breakby attribute Brand in page-by as shown below:
  

• Create a document using R1 as dataset; note that M1 values show as “--”
  

 
CAUSE
When a report is added to a Report Services document, the page-by attribute is not moved to the grid and this turns the report from a standard report to an OLAP report. 
Since the metric is defined using RunningSum function, there is no way to determine which single function (Sum or Count) should be used to dynamically aggregate the overall metric result. Thus dynamic aggregation nulls are returned in the document.
For more information regarding dynamic aggregation nulls, refer to the following Strategy Knowledge Base document:
KB15843: What is the function of the ‘Total subtotal function’ and ‘Dynamic aggregation function’ settings in Strategy SQL Generation Engine?
ACTION
Specify aggregation function, for example use sum as shown below:

After this, the document shows the correct result for M1 as shown below: