HOW DO I FIX GMAIL NOTIFICATION NOT WORKING ON IPHONE?
The reason behind this may be the disabled Gmail alerts. Gmail has a feature where users can choose whether or not they wish to receive notifications. If you are facing a similar problem as Gmail notifications not working on iPhone, you should ensure that the alerts are enabled. Open your Gmail application and click on the Menu. Go to the Settings next and select your account. From the list of options, tap on Notifications and select a notification level.