Epic/Feature: when clicking Unassigned Backlog nothing is shown if Tier 1 has the Portfolio selected

Issue Summary

On the Feature/Epic backlog, if you have on Tier 1 the Portfolio + PI selected you can see the Unassigned backlog section with items on it. When you click the button Unassigned Backlog, the panel that opens don't show these items.
If you have on Tier 1 a Program+ PI, when clicking the button for Unassigned Backlog it opens the panel with the items correctly.

Steps to Reproduce

1. Go to the Feature/Epic backlog
2. On Tier 1 select a Portfolio and PI
3. Click on the Unassigned Backlog button on the right corner

Expected Results

The panel would open and show the items on the unassigned backlog

Actual Results

The panel opens but shows nothing

Workaround

When the panel opens and don't show the items, click on the Advanced Button -> Clear.