With the introduction of arbitrary issue hierarchies in Portfolio Live Plans, the way Portfolio stores its hierarchy information has changed. Whereas with standard plans, Initiative/Epic links were stored as Issue Links, this information is now stored as an issue property that as of now is not visible in JIRA. That is, when you open your initiative in JIRA you do not see any information on the child epics. Only in case of Agile Epic / Story relationships this information is visible in JIRA since there is a dedicated custom field for this already, the Epic Link.
It would be great to make the hierarchy information used by Portfolio Live Plans visible in JIRA in a similar way as Epic/Story relationships of Agile / JIRA Software are visualized.