Sean Reiser I 100% agree that it should work :) Here is what code I have in my settings.php file.

if (isset($_ENV[‘PANTHEON_ENVIRONMENT’]) && php_sapi_name() != ‘cli’) {
// Redirect to https://$primary_domain in the Live environment
if ($_ENV[‘PANTHEON_ENVIRONMENT’] === ‘live’) {
/** Replace www.example.com with your registered domain name */
$primary_domain = ‘myawesomewebsite.com’;
}
else {
// Redirect to HTTPS on every Pantheon environment.
$primary_domain = $_SERVER[‘HTTP_HOST’];
}
if ($_SERVER[‘HTTP_HOST’] != $primary_domain
|| !isset($_SERVER[‘HTTP_USER_AGENT_HTTPS’])
|| $_SERVER[‘HTTP_USER_AGENT_HTTPS’] != ‘ON’ ) {
# Name transaction “redirect” in New Relic for improved reporting (optional)
if (extension_loaded(‘newrelic’)) {
newrelic_name_transaction(“redirect”);
}
header(‘HTTP/1.0 301 Moved Permanently’);
header(‘Location: https://'. $primary_domain . $_SERVER[‘REQUEST_URI’]);
exit();
}
// Drupal 8 Trusted Host Settings
if (is_array($settings)) {
$settings[‘trusted_host_patterns’] = array(‘^’. preg_quote($primary_domain) .’$’);
}
}