iOS Notification Service Extension not getting called

Here’s the payload I’m sending from the Firebase Admin SDK (Python)

messaging.Message(
        notification=messaging.Notification(
            body=data_message['body'],
            title=data_message['title'],
        ),
        apns=messaging.APNSConfig(
            payload=messaging.APNSPayload(aps=messaging.Aps(mutable_content=1, content_available=1, sound= "ting.wav"),
              notifee_options={
                'ios':  {
                    'critical': True,
                    'sound': "ting.wav",
                    'criticalVolume': 0.2,
                    'categoryId': "channelHigh",
                },
                'data': data_message
            }
            ),
        ),
        token=registration_token[args.device],
    )

Here’s my NotificationService.m (To debug, I’ve tried to modify the title of bestAttemptContent before sending it to the NotifeeExtensionHelper)

#import "NotificationService.h"
#import "NotifeeExtensionHelper.h"

@interface NotificationService ()

@property (nonatomic, strong) void (^contentHandler)(UNNotificationContent *contentToDeliver);
@property (nonatomic, strong) UNMutableNotificationContent *bestAttemptContent;

@end

@implementation NotificationService

- (void)didReceiveNotificationRequest:(UNNotificationRequest *)request withContentHandler:(void (^)(UNNotificationContent * _Nonnull))contentHandler {
    self.contentHandler = contentHandler;
    self.bestAttemptContent = [request.content mutableCopy];
  
  self.bestAttemptContent.title = [NSString stringWithFormat:@"%@ [SE]", self.bestAttemptContent.title];
    
  [NotifeeExtensionHelper populateNotificationContent:request
                                  withContent: self.bestAttemptContent
                                   withContentHandler:contentHandler];
}

- (void)serviceExtensionTimeWillExpire {used.
    self.contentHandler(self.bestAttemptContent);
}

@end

In foreground, notification is handled by RNFirebase’s onMessage() function. However, in the background or in quit state it just delivers the notification as-is, with no modifications. It doesn’t even change the title, which leads me to believe that the NSE isn’t getting called at all. Moreover, the setBackgroundMessageHandler isn’t taking effect either.

The only relevant logs I get from Xcode are:

[RNFBMessagingModule signalBackgroundMessageHandlerSet] [Line 95] signalBackgroundMessageHandlerSet called
[RNFBMessagingAppDelegate signalBackgroundMessageHandlerSet] [Line 74] signalBackgroundMessageHandlerSet sharedInstance.backgroundMessageHandlerSet was NO

but I’m very clearly setting the backgroundMessageHandler in my entry-level index.js:

import messaging from "@react-native-firebase/messaging";
import notificationHandler from './notificationHandler'

messaging().onMessage(notificationHandler);
messaging().setBackgroundMessageHandler(notificationHandler);

Any leads on what could be wrong?

Edit: I upgraded from 4.0.0 to 4.1.0 and RNFirebase from 13 to 14, but background notifications didn’t work previously either.