Similar issue here but another error. Just upgraded the whole stack (including beats) and started playing around with reports. Reports get generated (based on dashboard) but once I click on ‘PNG’ icon to down load, I get “Error downloading report” message. Kibana logs show a bizarre error indicating that it tries to connect to the localhost:5601 (why???) while my Kibana is not running on default URL at all. Obviously, I did not find anything about the respective configuration (I just hoped that maybe some specific definition for reporting is required in order to let the plugin know about Kibana’s URL).
{“type”:“log”,“@timestamp”:“2021-01-13T20:58:28Z”,“tags”:[“error”,“plugins”,“opendistroReportsKibana”],“pid”:29377,“message”:"Error: net::ERR_CONNECTION_REFUSED at http://localhost:5601/app/dashboards#/view/826ab760-ee8e-11ea-a949-4f7c89c35c0b?_g=(time:(from:‘2021-01-13T20:20:33.222Z’,to:‘2021-01-13T20:50:33.222Z’))\