We're sorry to report that we're currently experiencing an issue with global reports for Duo.
Right now, global reports for Duo fail due to leveraging an incorrect data source ("duo"). We are working to fix the issue as soon as possible so that the correct data source applies automatically.
Until we release this fix, you can work around the issue by changing the Duo global report's data sources to the following options:
Duo Security Admin Logs
Duo Security Auth Logs