Issue
When publishing a Nintex Workflow the error "The workflow name is used elsewhere on this site. Please choose another name.” occurs.
When looking through the site there is no existing workflow with the name that is being used when publishing.
Error Code
The workflow name is used elsewhere on this site. Please choose another name.
Resolution
Solution 1.
Empty the SharePoint recycle bin.
Publish workflow.
Solution 2.
Log into the Site of the O365 tenant with SharePoint Designer.
From the Objects tab in SharePoint Designer click Workflows.
Find the Workflow with the name that you are wanting to use and delete it.
Publish your workflow.
Additional Information
This issue can occur when a list has a Nintex Workflow published on it and the list is deleted without deleting the workflow from the gallery first.
This same error will occur when creating a workflow with SharePoint Designer as the error is coming from SharePoints Workflow Manager and not Nintex.