Thank you for contacting us, and sorry for the trouble caused. Please create a Link/publish a XD document using an option "Anyone with the link" under the Link access menu, so that the it will be accessible to the invited user. Do let us know if you need more info or any further assistance.
The setting of the link is exactly as you described it to me. Some colleagues had it open and not closed last week, and today they can't open it, but some others can. Maybe this has to do with how long a link stays open?