A group of Microsoft Products and technologies used for sharing and managing content, knowledge, and applications.
You may need to register the SharePoint workflow service again by specifying the scope name as below
Register-SPWorkflowService –SPSite "Site collection URL" –WorkflowHostUri "Workflow URL" -Force -ScopeName "SharePoint"
If the issue still persists, so try to Disable loop Back Check as mentioned at Disable the authentication loopback check
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