When I add to a document with Record and Show Changes enabled it says the new addition was made on the same date & time as the previous part of the document. To get it to register the correct date & time of the new addition I have to undo Record Changes then re-enable it.
Well, I think it’s by design.
Change times recorded per-session, not for each character entered.
This function is intended for multiuser environment, when multiple people can edit documents, and, to merge changes, it’s needed to know when and who made them (and for that, it’s enough to know when document was opened/saved).