Created attachment 129666 [details]
Test document with date field.
I use the German version of LibreOffice.
I created a new text document and added a date field with formatting "31. Dezember 1999" to the document.
On the screen is displayed: 15. Dezember 2016.
Then I save the document in the MS Office DOCX-Format and close it. After opening it again in LibreOffice it shows:
31. December 2016
This means, the language for the paragraph has been switched from German to English. I can now format the language for the paragraph to German again, but when I save and open again, I will get the english date again.
Test document attached.
Sounds like bug 99236
Yeah, let's dupe.
*** This bug has been marked as a duplicate of bug 99236 ***