I'm currently having issues with deleting the NintexWorkflowHistory List content. In the Site Settings > Manage Workflow History Lists, it shows that our NitexWorkflowHistory list has 30601 items. If I select the purge option with a filter of "Last Activity before" 01/01/2015 and a state of "Complete" and action the purge, nothing is deleted. I have also processed the same filter with both Cancelled and Error states. Still nothing is removed.
As per the screenshot below there are multiple items in this list dating back to 2013 and should have been removed.
I have also run the NWAdmin.exe PurgeHistoryListData and SyncTerminatedWorkflows, with relevant criteria to purge data. With the latter, I have run with the terminateDeletedItems parameter too.
I do not seem to be having much joy. Any suggestions?