Button states lost from time to time
When a button that usually has different states is added, I experienced that those button states are lost after the document is saved a couple of times. Buttons are only available in standard state then. If you want to have different states again, you have to delete the button and add it again from the library.
In general I experienced several problems when it comes to saving. I am the only one working on the document, but every now and then I get the message that the document has been changed by someone else.
Besides the button states also prototype connections and flow names were lost.
Thanks for filing a ticket! This seems like a bug and not a feature request, so you should definitely file this on the Community Support Forum. https://community.adobe.com/t5/adobe-xd/bd-p/xd?page=1&sort=latest_replies&filter=all