I just lost some work after opening a document. What was presented was by no means the latest version. I tried to refer to the document history and it's just greyed out. The document had been saved at least 8 times before this happened.
Sorry to hear about the trouble. Could there be any possibility that the file was overwritten? Please check if you are able to see the file at these locations and if they are different than the one you have currently:
Mac: ~/Library/Application Support/Adobe/Adobe XD CC