MassUpdate not displaying items when the Release/PI is set to Unassigned Backlog

Issue Summary

The Mass Move / Mass Delete found on MassUpdate.asp is not showing items when the Release/PI is set to Unassigned Backlog, even though there are items in the Release/PI Unassigned Backlog.
Noticed for Epic & Story (but may also affect Feature)

Steps to Reproduce

1. Go to MassUpdate.asp
2. Select Object to be Epic (or Story)
3. Select Program Increment - Unassigned Backlog
4. Select Program to be a suitable Program
5. Theme not required.

Example: https://alignsupport.jiraalign.com/MassUpdate?Programs=220&Releases=229

Grid	Grid Image	Grid Unassigned PI Results	Mass Move/Mass Delete	Unassigned PI Results
Epic		1 result		0 results
Story		2 results		0 results

Expected Results

Show results with PI set to Unassigned Backlog.

Actual Results

0 results

Workaround

Currently there is no known workaround for this behavior. A workaround will be added here when available