Thank you for providing more information. Based on the details you provided, it seems that the issue might be related to the token obtained from the token provider. Here are a few things you can try:
Verify that the token provider is configured correctly in the Azure portal. You can check the connection string and the access policies for your notification hub.
Make sure that the token provider is using the correct credentials to authenticate with the notification hub. You can verify this by checking the credentials in the respective push notification service developer portal.
Check if there are any issues with the certificate used to sign your app package. If the certificate is invalid or has expired, it can cause issues with the token provider.
Try using the EnableTestSend property again and see if it provides any additional information. You can also try using the Notification Hub REST API to send a test notification and see if it works.
If none of these steps help, please let us know and we can investigate further.