I recommend also looking over our documentation found here - this specifically calls out the deactivation of a system administrator and what to expect. 

Please consider submitting a ticket to the support team so we can assist in investigating this further. 

More information regarding the reporting canvas and its incremental rollout can also be found at https://experienceleague.adobe.com/en/docs/workfront/using/product-announcements/beta/canvas-dashboards-beta/reporting-canvas-beta-overview.