For years, we have been using

myDoc.SaveAs3(FullNewPath, (int)swSaveAsVersion_e.swSaveAsCurrentVersion, (int)swSaveAsOptions_e.swSaveAsOptions_Silent);

to save a document with a different file name.  In SW2016 some files will save with no problems, others that are almost identical are saved with the file name, but without anything in the file.  When I try do a regular save as in SW there is no problem.

I have also tried using the extension version

MyDocExt.SaveAs(FullNewPath, (int)swSaveAsVersion_e.swSaveAsCurrentVersion, (int)swSaveAsOptions_e.swSaveAsOptions_Silent, swExportPDFData, Errors, Warnings);

but it gives the same result.

Any ideas on what could be causing this?