Saving to .docx format don't save comments. There should be warning what says that or LibreOffice should save these. If there is no warning then people are going to lost hours and hours of work.
Created attachment 44780 [details]
Shows how are comments located in specific files
LibreOffice does warn each time you save to a non-ODF format, unless you have told it to not warn.
But yeah, it gives that warning even for utterly trivial documents, in cases where nothing is going to be lost.
So clearly that warning is just ODF marketing.
Giving a real warning beforehands only when the document actually has such content that won't be saved properly in the format the user wants to save in is much harder. In theory that would require actually going through the save code path twice, first into the bit bucket, checking if there is something that can't be saved in the format in question, and if yes showing the warning dialog, and only then if the user accepts the loss of data, the real save.
Maybe LO should simply warn *after* saving that some contents was lost in the used format, and offer to do an automatic backup as ODF, too? (Assuming ODF formats indeed can save everything that can be produced in LO, or loaded into LO, of which I am not 100% certain.) Maybe it should do that silently? Nah, that would be bad from a confidentiality point of view.
*** This bug has been marked as a duplicate of bug 33463 ***
@Tor: For the record ... The "simple" warning message is caused by the fact that we don't know what gets lost if saving in foreign file formats (according to my discussions with Michael Meeks).
It would be desirable to really know what gets missed - and then inform / warn the user accordingly ("minor loss of fidelity (table formatting)" / "loss of information (comments)" / ...). Checking this during / directly after saving would be totally sufficient, since all required information is still available within LibreOffice to manually save in ODF.