Case mismatches between the CustID values on Subset and CustID values on Profile can cause issues with HSS.
Run the following in SQL Server Management Studio to identify records where the case is different between the HEATCAI.CustID and the Profile.CustID:
SELECT DISTINCT(CustID), CallID
WHERE (CustID IN
(SELECT CustID FROM Profile)
AND CustID Collate SQL_Latin1_General_CP1_CS_AS NOT IN
(SELECT CustID FROM Profile))