Assuming the Portfolio hierarchy is as follows:

    Initiative

        |_ Strategy

            |_ Epic

                |_ Story / Bug

Currently  it is not possible to link a Bug to a Strategy or an Epic to an initiative. You need to create the full hierarchy in order to attach an item under its initiative.

This feature request is to allow this:

So if a bug is under a Strategy but does not have an Epic, it should appear in a section "Issues without parent Epic" under the Strategy.