Lib is v.0.59. DB has the collection "users", but cannot get.
B4X:
Dim users As CollectionReference = fs.collection("users", "")
users.limit(10).fetch("UserFetch")
This is in your example, no error - but no records from db (exists 1).
B4X:
Dim users As CollectionReference = fs.collection2("users")
users.limit(10).fetch("UserFetch")
This does not work, seems not initialized, but users is not Null:
B4X:
java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String java.lang.String.toLowerCase(java.util.Locale)' on a null object reference
I seems to me that the trouble reason is not the rules. Some global setting of the db that has in your DB.
Also, my example code has no FirebaseNotifications, but it's also not the reason.