Columns from External Hypercubes Display Empty

Starting with version 11, MITS Discover has the ability display columns from multiple hypercubes in a single report.  You can learn more about the feature here:

Add Columns from External Hypercubes

A common question to support asks why some columns show up empty when using the External Columns feature.  Consider the screenshot below.

In this report, we have three columns from the SALES cube and are drilled down by PRODUCT.

If we add a column from the AR cube, as shown in the next screenshot, you can see column is mostly empty.

This is because the report is drilled down by Product in the SALES cube and there is no matching drill down path for Product in the AR cube.

This is also why you have a top total displaying in our example.  The top total is available in both cubes, so it will display.  It is the lack of matching drill down paths between the two cubes that causes the column to be blank.

However if we change the drill down path to one that exists in both the SALES and AR cubes, then the column in our report will be populated as expected.  Here we changed the drill down path to Bill to Customer.  That is a drill down path that exists in both the SALES and AR cubes.