Using Appointments+ - Calendar API failing "The OAuth client was deleted."

Hey guys,

I have tried everything I can to make the calendar authentication work. Any time I click on the "Generate Your Access Code" button I get the following:

401. That’s an error.
Error: deleted_client
The OAuth client was deleted.

I have googled the issue. I have tried re-installing the plugin, etc. I have cleared all server caches. It appears it's trying to reference an old API key that we have since removed. How do I make the system reset and take a new key?