How to use Timer in the new Widget API?

I'm building a new widget for one of my apps, and the new Text initializer init(_:style:) is not enough for me. I need to have some control over which NSCalendar.Units are displayed, so I'm trying to use DateComponentsFormatter here. I have to use my own Timer because of that, and here's my code.

Code Block swift
struct TimerText: View {
    let date: Date
    let allDay: Bool
    let unitFlags: NSCalendar.Unit
    private let timer = Timer.publish(every: 1, on: .main, in: .common).autoconnect()
    @State var duration: String?
    init(date: Date, allDay: Bool, unitFlags: NSCalendar.Unit) {
        self.date = date
        self.allDay = allDay
        self.unitFlags = unitFlags
        updateDuration()
    }
    func updateDuration() {
        duration = systemDurationString(date, allDay: allDay, unitFlags: unitFlags)
    }
    var body: some View {
        Text(duration ?? "—")
            .font(.system(.title, design: .monospaced))
            .onReceive(timer) { _ in
                updateDuration()
            }
    }
}

systemDurationString function uses DateComponentsFormatter inside and returns the formatted string.
Unfortunately, onReceive callback never gets called. I thought this might be a problem with RunLoop that I've chosen, but it's seems like .current doesn't work either.