I did not find a documentation wheather or not you support the “w:dirty” attribute on fields. Can you let me know if you are updating fields if the dirty flag is set?
I am referring to the dirty flag described in §17.16.18 and §17.16.19 of OpenXML standard ISO 29500-1:2012.
[Edit] Additional question: Do you support the “w:fldLock” attribute as well?
Also see https://blogs.msdn.microsoft.com/pfedev/2010/08/08/openxml-how-to-refresh-a-field-when-the-document-is-opened/ for the attribute details.