Can't get sites added back to dashboard after deactivate

Deactivated the WPMU Dev Dashboard plugin, then reactivated it. Now the websites are listed on the left in red in the managewp dashboard with error “ reload site

Authentication failed. Deactivate and activate the ManageWP Worker plugin on this site, then re-add it to your ManageWP account.”

Why can’t it connect when the plugin is already installed (it was working before I deactivated & reactivated the plugin).