Is Sub-task an issue type that is available in your project? If it is, the button should be there automatically. If that issue type is not available in your project, a JIRA administrator will have to modify the Issue Type Scheme for your project to make it available.
Catch up with Atlassian Product Managers in our 2020 Demo Den round-up! From Advanced Roadmaps to Code in Jira to Next-Gen Workflows, check out the videos below to help up-level your work in the new ...
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