Hi Will,
I faced the same issue. The work around is do not use the Counter option under the exception aggregation selection tab.
Create another CKF. Use a constant '1' and then under the exception aggregation tab select "Summation" and enter the reference object u want.
Use this CKF in place of the current CKF that you are using and your query should successfully run with the BWA.
Kindly assign points if it helps.
Sunny C