MessagingStyle Not Displaying Text

New to Android development and I’m trying out the latest addHistoricMessage, and I’m missing something because it’s not displaying anything. On rare occasion the addMessage text is displayed, but the addHistoricMessage is never displayed. addMessage works consistently when using NotificationCompat, but NotificationCompat doesn’t appear to have addHistoricMessage.

Any thoughts appreciated - using androidx.appcompat:appcompat:1.0.2 and compileSdkVersion and targetSdkVersion are both 28.

An example of what I’m seeing is:

Test button that calls notification:

fun test(view: View) {
    val job = GlobalScope.launch {
        val repository = DataRepository.getInstance(Db.getDb(this@MainActivity))

        AlarmReceiver().notifyTest(
                this@MainActivity,
                repository.upcomingDetail(9),
                arrayListOf("Hi!", "Miss you!", "Hello!")
        )
    }
}

Notification methods and related (less important code removed):

fun notifyTest(context: Context, upcoming: UpcomingDetail, top3Sent: List<String>?) {
    //...

    @TargetApi(Build.VERSION_CODES.P)
    when (Build.VERSION.SDK_INT) {
        in 1..27 -> {
            with(NotificationManagerCompat.from(context)) {
                notify(upcoming.id.toInt(), legacyNotificationBuilder(
                        context,
                        upcoming,
                        noteIntent,
                        contentPending,
                        disablePending,
                        deletePending,
                        postponePending,
                        top3Sent
                ).build())
            }
        }
        else -> context.getSystemService(NotificationManager::class.java)
                .notify(upcoming.id.toInt(), notificationBuilder(
                        context,
                        upcoming,
                        noteIntent,
                        contentPending,
                        disablePending,
                        deletePending,
                        postponePending,
                        top3Sent
                ).build())
    }
}

@RequiresApi(Build.VERSION_CODES.P)
private fun notificationBuilder(
        context: Context,
        upcoming: UpcomingDetail,
        noteIntent: Intent,
        contentPending: PendingIntent,
        deletePending: PendingIntent,
        disablePending: PendingIntent,
        postponePending: PendingIntent,
        top3Sent: List<String>?
): Notification.Builder {
    val recipient: android.app.Person = android.app.Person.Builder().setName("Darren").setImportant(true).build()
    val you: android.app.Person? = null

    val messageStyle = Notification.MessagingStyle(recipient)
    val message1 = Notification.MessagingStyle.Message("Hello!", Instant.now().minusSeconds(10 * 60).toEpochMilli(), recipient)
    messageStyle.addHistoricMessage(message1)
    messageStyle.addMessage(Notification.MessagingStyle.Message("Hi", Instant.now().toEpochMilli(), recipient))

    val remoteInput: android.app.RemoteInput = android.app.RemoteInput.Builder(upcoming.id.toString()).run {
        top3Sent?.let { setChoices(top3Sent.toTypedArray()) }
        build()
    }

    //...

    val inputAction = Notification.Action.Builder(0, context.getString(R.string.button_edit), inputPending).run {
        addRemoteInput(remoteInput)
        build()
    }

    return Notification.Builder(context, "Input").apply {
        setSmallIcon(R.drawable.ic_stat)
        style = messageStyle
        setAutoCancel(true)
        setCategory(Notification.CATEGORY_REMINDER)
        setColor(ContextCompat.getColor(context, R.color.secondaryDarkColor))
        setContentIntent(contentPending)
        setDeleteIntent(deletePending)
        setGroup("notifications")
        setOnlyAlertOnce(true)
        setVisibility(Notification.VISIBILITY_PRIVATE)
        addAction(inputAction)
    }
}