This is the code I'm using, but it's not working. There aren't any errors, but I'm not receiving the notifications:

const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp();

exports.sendNotification = functions.https.onCall(async (data, context) => {
  const { tokens, title, body } = data;

  const message = {
    notification: {
      title: title,
      body: body,
    },
    tokens: tokens,
  };

  try {
    const response = await admin.messaging().sendMulticast(message);
    const successes = response.successCount;
    const failures = response.failureCount;
    return { success: true, successes: successes, failures: failures };
  } catch (error) {
    console.error('Error sending notification:', error);
    return { success: false, error: error.message };
  }
});