The plugin is Jira Gantt Chart. It added a menu item but it should have a drop-down with various selections. From the doc I read, Jira may need to be restarted. Our domain is myphtcorp. Can you restart Jira please?
We are not Ondemand/Cloud Atlassian support, we're a community of end-users.
Please raise this with OnDemand support - https://support.atlassian.com
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