I recently copied a series of similar formula columns from one Jet Report to another and accidentally copied a field column that did not exist in the new Jet Report. When it ran, I got the generic Pivot Table could not be refreshed error. But there were no errors. It was only after I deleted the sheet that had the Pivot Table and just ran the Jet Report to create the NL Table that I got an invalid field error.
Having an additional validation available for Jet Report Fields and Link Fields would help prevent wasted time debugging. Or better yet, when a paste operation is performed, check any newly created or edited Field names against the NL table and flag any that do not exist.