The button to add someone to the XD doc is missing on all of my files.
Sorry to hear you're unable to invite members to the XD file. This is definitely a strange issue.
Have you tried signing out of XD and the Creative Cloud Desktop app, restarting the machine, and then launching XD from the Creative Cloud Desktop app?
Are you the owner of the file?
We will try our best to help.
Hope you're doing well!
We would like to follow up on your issue. Are you able to resolve the issue? Please feel free to update the discussion if you need further assistance from us.
We would be happy to help.