On this task page, the Build Baron Plugin does not display the BFG ticket that was automatically created.
The ticket information is retrieved through an API call (plugin/buildbaron/created_tickets/) that returns a 500 error with a "HTTP request returned unexpected status `404 `" error message.
The message appears to come from the GetJIRATicket() function.
A 404 for the JIRA API call could happen if the ticket key is invalid.
This key is retrieved from Evergreen events by the Build Baron Plugin here.