If you're having issues assigning a site to users because the facility is missing, follow the steps below:
Login using client credentials
Go to the users list
Find the user name
Change the facility from origin to another facility, save, and then change back another facility to the origin facility and save.
Go to resident auto assign, unselect and reselect, then save.
After this, use the admin login to go to the admin.
Go to assign users to the facility.
Search the user's name.
Unselect all facilities, save, and reselect all facilities, then save.