It seems that beta 3 broke StoreKit Testing when running against an iOS 26 simulator device. Specifically, when validating product IDs, the debug console displays messages like the following:
[492a4cfa_SK1] Could not parse product: missingValue(for: [StoreKit.ProductResponse.Key.price], expected: StoreKit.BackingValue)
[492a4cfa_SK1] Could not parse product: missingValue(for: [StoreKit.ProductResponse.Key.price], expected: StoreKit.BackingValue)
[492a4cfa_SK1] Could not parse product: missingValue(for: [StoreKit.ProductResponse.Key.price], expected: StoreKit.BackingValue)
[492a4cfa_SK1] Could not parse product: missingValue(for: [StoreKit.ProductResponse.Key.price], expected: StoreKit.BackingValue)
[492a4cfa_SK1] Could not parse product: missingValue(for: [StoreKit.ProductResponse.Key.price], expected: StoreKit.BackingValue)
[492a4cfa_SK1] Could not parse product: missingValue(for: [StoreKit.ProductResponse.Key.price], expected: StoreKit.BackingValue)
[492a4cfa_SK1] Could not parse product: missingValue(for: [StoreKit.ProductResponse.Key.price], expected: StoreKit.BackingValue)
[492a4cfa_SK1] Could not parse product: missingValue(for: [StoreKit.ProductResponse.Key.price], expected: StoreKit.BackingValue)
In addition, the SKProductsResponse (I am using the original StoreKit API), lists all requested product IDs in invalidProductIdentifiers. The products array is empty.
StoreKit Testing behaves as expected when Xcode 26 beta 3 is run against an iOS 18.4 simulator device.