Wiki updated on
new rules on GPU refunds
In most cases, the Global Premier Upgrade will be considered used if any segment of an itinerary is upgraded or flown. However, for travel which includes segments in United Polaris business class or United Polaris first class, the Global Premier Upgrade will be re-deposited if the United Polaris business class or United Polaris first class segment(s) could not be upgraded.
There had been some uncertainty with the older rules if a failed PS segment on a domestic itin could trigger a GPU refund. With PS not considered a Polaris flight, it appears a PS failure will not lead to a refund in the future.