Flutter setState is not reloading page - flutter

Question

I am building a Flutter app that allows users to create locations and then have those locations uploaded to a database and shown to other users on a map. I have gotten the database and displaying of locations to work properly, but I want the map, a Google Map, to dynamically reload after the user has created a location and is returned to the map screen.
Right now, I am using Firebase Realtime Database to listen for changes and trying to update the map accordingly after the user has clicked on the button to create a new location. Here is the code for that:
Navigator.push(
context,
MaterialPageRoute(builder: (context) => const LocationCreation()),
).then((valuef) {
locationsRef.onValue.listen((DatabaseEvent event) {
final data = event.snapshot.value;
if (event.snapshot.value != null) {
allMarkers = {};
final map = data as Map<dynamic, dynamic>;
map.forEach((key, value){
print(value['name']);
allLocations.add(value);
// Code to create a Marker object called marker
}
);
setState(() {
allMarkers.add(marker);
});
});
}
});
I know this code is reached, because the print statement is being called and the correct names are being printed out, including the name of the newly created location. However, the map screen is not being updated with the new locations and their markers.
The Google Map is being built in the build function as so:
GoogleMap(
scrollGesturesEnabled: true,
onMapCreated: (onCreated),
initialCameraPosition: CameraPosition(
target: _center,
zoom: 11.0,
),
markers: allMarkers,
),
And here is the onCreated function:
print('here again');
mapController = controller;
final snapshot = await locationsRef.get();
final map = snapshot.value as Map<dynamic, dynamic>;
setState(() {
allMarkers.clear();
map.forEach((key, value) {
allLocations.add(value);
//Code to make a Marker called marker
allMarkers.add(marker);
});
});
The print statement is called once upon initial building of the app, but is not called again after a new location has been created and the user is returned to the map screen.
allMarkers is not being initialized within the build function, which I found was a common problem for others.
Each time I try to make a new location, the database will store the new location and the print statement within the listen for new database event will be called, but it seems that Flutter does not detect a change to allMarkers. I have also tried allMarker.clear(), but the problem is the same. I have also tried to move the call to setState(), but nothing has worked.