Issue Summary

When navigating to the backlog view of Epics with a Program and no PI selected. If you enable the estimation "T-Shirt Size" column shown you'll find that some Epics have null values despite estimations being set for multiple PIs. You'll also notice that the T-Shirt estimation conversation for Epics with multiple PIs doesn't roll up correctly.

Steps to Reproduce

1. Step 1 - Set a portfolio with T-shirt size estimations
2. Step 2 - Ensure there are 5 PIs available
3. Step 3 - Create multiple Epics (5+) & associate all 5 PIs to each Epic
4. Step 4 - Randomly select T-Shirt sizes for each PI estimation
5. Step 5 - Navigate to the backlog view with T-shirt estimations enabled via the column shown
6. Step 6 - Validate estimations for the program & PI & program & no PI

Expected Results

On backlog, if no PI is selected T-shirt size for epic  / capability should show the t-shirt size that is configured for the "initial" t-shirt size.(T-shirt sizes should never be summed across PIs)

Actual Results

Epics appear to be showing the incorrect T-shirt sizes when there is no PI set in tier one.

Workaround

No workaround for this bug at this time, but when there is one we'll be providing an update.