openoffice sdk c# error "File contains corrupted data" but opens fine in Calc

Question

Brand new to OpenOffice and having a problem from the start. Just installed the latest NuGet version of DocumentFormat.OpenXml in VS 2022 and I'm trying to open and save an .xlsx file as Tab delimited in C# but get an error but get this error, "File contains corrupted data", when trying to open the file with:

using (SpreadsheetDocument document = SpreadsheetDocument.Open(SourceXlsxName, false))

I can open the file in Excel as well as Calc. Not sure where to start looking for the cause of the problem.