Published scene services could not be deleted, with "Unable to delete item" messages and log details: "ERROR 999999: Something unexpected caused the tool to fail. Contact Esri Technical Support (http://esriurl.com/support) to Report a Bug, and refer to the error help for potential solutions or workarounds. Unexpected '}'; state : Empty; buffer : }}]".
This issue is not reproducible in ArcGIS Enterprise. If the issue persists, contact Esri Support Services as a new reproduction case is needed to continue the investigation.