Can't save file as docx - Windows 8

Tried copying and pasting the text from a document in Microsoft WordPad into LibreOffice, without any changes to the text in the original document in terms of ‘formatting’ except hitting enter a few times between paragraphs, and saving it as a docx file, but recieved a notification box saying, “This document may contain formatting or content that cannot be saved in the currently selected file format ‘Microsoft Word 2007-2013 XML’. Use the default ODF file format to be sure that the document is saved correctly.”

So, I closed LO entirely, reopened it with a fresh, new LO Writer document, typed in some random text without touching any formatting tools, and then tried saving it as a docx file, but received the same response.

Running Windows 8, uninstalled MS Office 365 after installing LO…

Any ideas?

You always get this warning when not saving in default odt format. Try it and see what happens. You will usually find that it works OK.

This is a standard warning that LO gives before saving to non-native formats. It does this because the support for these formats is not perfect. Most simple documents will translate to the other formats fine however. You can just override the warning and see how the file turns out. If you want to turn off the warning, and/or set LO to save to .docx by default, you can do that in Tools / Options / load and save / general.