Accounts for Kemisphere are synced through AD and Azure AD. What we've found is that when someone leaves the company, their account is disabled and a flag is unset on their Kemisphere profile so as to not surface the user in searches. When they are reactivated at a later date, they will not show up because this flag will remain unchecked. In these instances, someone with Kemisphere CMS access will need to go into the user's profile in the Security > Users CMS menu, and on the Properties tab, they can check the box next to "Discoverable". This will allow the user to once again surface in searches and within the corporate structure of the site.