Excel Sync Define Names plug-in generates an error in the CompleteAssignment background job: Error Updating excel define Names to SharePoint column.
Foundation 11.2.12 and higher
One of the potential reasons for this error is that the column type of the SharePoint column doesn't match the data type in Excel Advanced Properties.
Additionally if a Define Name in Excel has a bad reference, the Excel Sync Define Names will fail, even if the Define Name range isn't being promoted to SharePoint. This is because the workflow constructs the Excel in Spreadsheet Gear from the stream of bytes in SharePoint and can fail on these bad references.
Remove any bad references in Define Names within Excel and any references to the these Define Names to ensure the bad reference isn't regenerated.
Ensure that all column data types in SharePoint List Settings and data type in Excel Name Manager match.
If the issue is still not resolved, enable the SVService logs and submit a ticket to Support for analysis, including these logs, a screenshot of the SharePoint library entry and a copy of a data file that is failing.