I created a Jira ticket (MCM-21 for reference), and tried to set it up as a child to MCM-9. I went into MCM-9, clicked on the + and 'Create a child item'. Then I clicked on 'Choose Existing', and got a list of possible tickets I can use to become a child of MCM-9. However, MCM-21 was not on the list. Does anybody know why it wouldn't be there?