This error occurs when I view my data in Web Report Studio Help. The data value is one of the Product ID
This error can appear for promoted reports and for new reports if the multi-edit feature is used to change data item properties in the information map.
As a workaround, follow these steps:
For measures, and make sure that the Default aggregate function has a value.
For categories, make sure that COUNT(argument) is displayed (but grayed-out) in the Default aggregate function list.
If it is not, then select the Measure radio button and then switch back to Category. COUNT(argument) should now be filled in.
Did this show while you create a new report ?
If I am not wrong all you have to do is ensure that the values are present and not missing .