Can you post an excerpt from your kibana logs when the reporting job fails? Kibana should be writing errors to the log indicating what happened.
Can you try following the troubleshooting steps at the bottom of this page for your particular error message? https://www.elastic.co/guide/en/kibana/master/reporting-troubleshooting.html#_literal_caught_error_spawning_chromium_literal
cc @tsullivan/ @joelgriffith
Thanks
Rashmi