PHP Not Running On Page Until Refresh - php

Question

bit of a strange one that I've not been able to resolve for months so I finally have given in and have come here for the answer. Hopefully.
I have the below shortcode that when ran returns the phone number depending on what variable has a value. This PHP code works as expected, the one thing that doesn't work as expected however, is the first ever page load.
When someone goes to the site for the first time (or in incognito mode) the shortcode doesn't output anything, however, refresh the page just once and it'll display the output of the correct value and I have no idea why.
<?php function gw_cookie($atts) {
extract(shortcode_atts(array(
"value" => ''
), $atts));
$getVariable = isset($_GET[$value]) ? $_GET[$value] : '';
$newGetVariable = str_replace('_', ' ', $getVariable);
$cookiePhone = isset($_COOKIE[$value]) ? $_COOKIE[$value] : '';
$acfField = get_field('page_cookie_'.$value.'');
$optionsACF = get_field('options_company_details', 'options');
$area = $optionsACF['options_area'];
$phone = $optionsACF['options_telephone'];
if(!empty($cookiePhone) && $cookiePhone !== 'undefined') { //If cookie is not empty do the following
echo '1';
} elseif(!empty($newGetVariable)) { //If cookie is empty and get variable is not
echo '2';
} elseif($acfField) { //If ACF field is not empty do the following
echo '3';
} elseif ($value == "phone") {
return '4';
}
} add_shortcode("gw-cookie", "gw_cookie");
This codes file is being imported into the functions.php file using the following line:
require_once( __DIR__ . '/shortcodes/gw-cookies.php' );

Answer 1

A cookie itself would be created on the first run and your criteria requires cookiePhone which is why you have to refresh to make it work.
As per the comments, change:
$cookiePhone = isset($_COOKIE[$value]) ? $_COOKIE[$value] : '';
to:
$cookiePhone = isset($_COOKIE[$value]) ? $_COOKIE[$value] : NULL;