Commented Unassigned: Problem with XLSX (XSSF) [13046]

Hi all,
I'm an Italian user of NPOI (with bad written English) ;)

I have a problem with xlsx generation. When I open the spreadsheet created with NPOI, Excel return me this message:
"Excel found an unreadable content"
but it opens correctly the file.
I have tried to download and re-compile sources from (github - https://github.com/tonyqus/npoi) with the same issue.
---------
I also have a problem with "AutoSizeColumn" in XSSF workbook ... this function not work properly.

Thanks,
Valerio
Comments: ** Comment from web user: Valerio81 **

Hi tonyqus,
this is the xlsx generated.

I have tried to set CultureInfo to "us-US" as suggested to another post, but with no success.

Are there any software that validate xlsx files? Messages from Excel are not useful.