Created attachment 124780 [details]
ODT file with field and cross-reference to the field

In order to get correct numbering of illustrations, I use numbered field in this way:

Insert > Fields > Other > Variable, choosing Number range > Illustration

and them refer to it using a cross-reference:

Insert > Fields > Other > Cross reference, choosing Illustrating > Number

This works fine within LO, but if I save as .docx then the cross-reference is lost in the saved file. When I open the file (in LO or in Word), the cross-reference number is replaced by the word "Illustration" (and is no longer a field).

A sample ODT file is attached. To see the bug, open the file in LO, save it as .docx, close and re-open the file in LO or Word.

Lars J

Using LibreOffice version 5.1.2.2 on Windows 10