We have JIRA Core - Server. I need to move sub-tasks from 1 project to another. I export the sub-tasks via CSV, made the adjustments to Parent ID and Issue ID, and used the CSV import tool. I receive an error that the Parent ID is invalid and none of my sub-tasks will import. So I created a 'test' sub-task in said Issue. I exported and found that the Parent ID matches PERFECTLY. I cannot find much documentation in the Atlassian 7.3 for importing sub-tasks (older documentation discusses it, but their screens have obviously changed since then).
How are you importing sub-tasks correctly with the Parent ID?