🔔 [FCM] getInitialMessage() returns null on notification tap (data-only payload, app terminated)

[RahulSharma1224]

Hi everyone 👋,

I'm implementing FCM with only data payload (no notification field) and handling custom local notifications using flutter_local_notifications.

✅ Works:
Notifications are received and displayed via flutter_local_notifications.

onSelectNotificationResponse works in foreground & background.

FirebaseMessaging.onMessage and onMessageOpenedApp work in active/paused states.

❌ Issue:
When the app is terminated, and a notification with only data is tapped:

getInitialMessage() returns null

onSelectNotificationResponse is not triggered

Action buttons (e.g., "Reply", "Cancel") do not respond

Custom sounds work only when app is in foreground/background, not terminated

❓ What I’ve tried:
Using flutter_local_notifications with payload

Handling notification tap via onSelectNotificationResponse

Using getInitialMessage() in main.dart

Setting click_action: FLUTTER_NOTIFICATION_CLICK

Setting high priority in FCM

🔍 Goal:
Handle action button callbacks

Open specific screens on notification tap

Play custom sounds

All while app is terminated (cold start)

📱 Target:
Android & iOS (latest OS versions)