AttributedString in App Intents

In this WWDC25 session, it is explictely mentioned that apps should support AttributedString for text parameters to their App Intents.

However, I have not gotten this to work. Whenever I pass rich text (either generated by the new "Use Model" intent or generated manually for example using "Make Rich Text from Markdown"), my Intent gets an AttributedString with the correct characters, but with all attributes stripped (so in effect just plain text).

struct TestIntent: AppIntent {
	static var title = LocalizedStringResource(stringLiteral: "Test Intent")
	static var description = IntentDescription("Tests Attributed Strings in Intent Parameters.")
	
	@Parameter
	var text: AttributedString
	
	func perform() async throws -> some IntentResult & ReturnsValue<AttributedString> {
		return .result(value: text)
	}
}

Is there anything else I am missing?