add_attachment in not working with wp_get_attachment_image_src

This code is not working

add_action('add_attachment', 'example_file_added');

	function example_file_added( $attachment_id ) {

     $attachments = wp_get_attachment_image_src($attachment_id,"medium");

     var_dump($attachments);

	}

**return:** Not good (because attachment not medium link)

array(4) {
        [0]=> string(63) "https://example.com/wp-content/uploads/2015/09/example.jpg"
        [1]=> int(1)
        [2]=> int(1)
        [3]=> bool(false)
    }

is not medium link, in my opinion this bug..

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But this is working with edit_attachment…

add_action('edit_attachment', 'example_file_edit');

	function example_file_edit( $attachment_id ) {

     $attachments = wp_get_attachment_image_src($attachment_id,"medium");

     var_dump($attachments);

	}

**return:** Is good (because medium link)

array(4) {
        [0]=> string(63) "https://example.com/wp-content/uploads/2015/09/example-500x400.jpg"
        [1]=> int(500)
        [2]=> int(400)
        [3]=> bool(514145)
    }