Mysteries of why the "same" (version and subversion differences unknown) behaves differently for Microsoft products is a fact of life.
Once upon a time I worked in shop that was running Office suite on Windows 95, 98 and another I don't remember. We had an application involved for converting Word documents to the file format a production print company wanted.
Word documents with the same font going through the converter had interesting problems such a bullet lists appearing as bullets (the actual dot version) , right arrows or pointing hands depending on whose computer ran the conversion. Out of 15 computers in the office only one would render the document correctly.
Notice that you have a note about correcting XML. XML files are basically text. You can change the XLSX extension on a file to ZIP (yes Windows will complain). Then access the XML pages in the ZIP file. You might see the problem text result that way IF you don't let Excel try to fix the file.
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