Issue
When targeting a workflow using the "-workflowname" operator in the "PurgeWorkflowData" command, some or none of the associated data is removed. After narrowing down the range of data using other operators it is still failing to remove workflow data.
Resolution
The same stored procedure being used by the NWAdmin tool can be run by using the following SQL Query against the Nintex Content database:
USE [Your Nintex Content DB]EXEC dbo.PurgeWorkflowData @workflowname = 'Workflow Name'