Hello Rami,

Thanks for reaching out to us. The issue here is the "DIE" part in hook, this part will stop the code from executing. There is the hook 

function amelia_hook() {
    error_log('Amelia hook triggered');
    die('Amelia hook triggered');
}
add_action('amelia_before_appointment_added', 'amelia_hook');

function my_custom_function($appointmentData) {
    error_log('Amelia hook triggered');
    die('Amelia hook triggered');
}

add_action('amelia_before_booking_added', 'my_custom_function');

amelia_before_appointment_added is for the backend booking 

amelia_before_booking_added is for frontend booking

When using "die" part, the code wont execute and the appointment wont be stored.

You are welcome, Rami.

I'm glad that we can help. 

Should you have any other questions or issues, feel free to reach out to us and we will kindly provide assistance.