NSUserActivity is no longer responding to setSuggestedInvocationPhrase?

Is anybody else seeing problems with NSUserActivity and the Intents extension after upgrading to Xcode 11.4 and/or iOS 13.4? I have a project that was working the last time I built it, but that was prior to the 11.4 release. Today, when trying to build it I find that a debug build seems to work fine when attached to a debugger. But if I launch the app directly from Springboard I will get a crash and an unrecognized selector error message in the console as soon as I call setSuggestedInvocationPhrase.

I made a simple test case for my Feedback Assistant report. here's the core function that exhibits the problem.

import SwiftUI
import Intents

struct ContentView: View {
    var body: some View {
        if testForSelector() {
            return Text("You can call setSuggestedInvocationPhrase")
        } else {
            return Text("setSuggestedInvocationPhrase will crash if you call it.")
        }
    }
}

extension ContentView {
    func testForSelector() -> Bool {
        let activity = NSUserActivity(activityType: "Testing Activity")
       
        return activity.responds(to: #selector(setter: INIntent.suggestedInvocationPhrase))
    }
}

I'm guessing that I've done something super-weird to cause this, but it *looks* very straightforward. Hoping somebody else has seen something similar.

If you do see something similar I submitted a Feedback Assistant at FB7645803.