When viewing the 'View Potential Duplicates' screen (PDQ screen from here on), no duplicate records are shown even though the left-hand column indicates that there are duplicates. There are the three most common causes for this:
1. Your SQL server has a hyphen (-) in its name.
If this is true, navigate to C:\Program Files\c360 Solutions\V3\Config and find c360.duplicatedetection.config The key you are searching for is toward the bottom of the file: <add key='c360.DuplicateDetection.CRMDBServerName' value='sql-server'/>. The fix is to simply put the SQL server name in between brackets, like so: <add key='c360.DuplicateDetection.CRMDBServerName' value='[sql-server]'/>
2. 'SETUSER' command may be failing.
This is especially evident if you are using Windows authentication. Possible solutions are to use SQL authenticationin your connection strings, or if you are already using SQL authentication, change the SQL account to something with more privileges. (The SQL 'SETUSER' command requires administrative privileges)
3. The database connection string may be wrong.
If you have run the c360 troubleshoot page and it shows that your connection string is valid, it may be that the connection string in c360.duplicatedetection.config does not match. Find the 'EncryptedDataBaseConnectionString' key and delete it from c360.duplicatedetection.config-- this will make Duplicate Detection refer to the connection string in c360.config instead.