I have just installed version 3.0,3 of Zendesk for JIRA on our JIRA On-Premise version 7.1.4. It installed without any issues. When I click on Configure in the Manage Add-Ons page it tries to load the add-on but eventually times out with the message "Add-on Zendesk for JIRA is not responding. Wait or cancel?"
Does anyone have any ideas on what is happening here?