I defined several topics and subscribed FCM tokens to them. Initially, all devices received notifications when sending to the topic, but after some time, some devices stopped receiving them. If I send notifications to those specific devices directly (using their FCM tokens instead of the topic), they receive the messages.
This is not something that is managed by B4A. Assuming that you implemented it correctly, and are sending the messages with the B4J code then the problem is with Firebase.
it looks like the issue i got here. After 2 days the devices will stop receiving notifications. Only way to get it working again was by deleting the app and reinstall it.
After i made this modification all devices continue receiving notifications for much longer time. "under test"
Note: I'm not using B4xpages
B4X:
Private Sub Receiver_Receive (FirstTime As Boolean, StartingIntent As Intent)
' If FirstTime Then
fm.Initialize("fm")
' End If
fm.HandleIntent(StartingIntent)
Log("init FBM")
End Sub