useDeliveryGroups() returning option with undefined selectedDeliveryOption in Shop Pay flow but working as expected in regular checkout

[rbarreca]

Please list the package(s) involved in the issue, and include the version you are using

"@shopify/ui-extensions": "2024.07.x",
"@shopify/ui-extensions-react": "2024.07.x",

Describe the bug

useDeliveryGroups() returning option with undefined selectedDeliveryOption in Shop Pay flow but working as expected in regular checkout.

Steps to reproduce the behavior:

1. Create a custom shipping (not sure if this is pertinent, but it's all we use so including)
2. Create a thank you block extension with const deliveryGroups = useDeliveryGroups(); console.log(deliveryGroups);
3. Run it with regular checkout flow then with Shop Pay

Expected behavior

In Shop Pay, selectedDeliveryOption is undefined while in regular checkout it's working as expected.

Screenshots

Additional context

Relevant to #1173