PHP script not reading set cookie in Safari OSX and iOS

Problem: verified cookie set in PHP and visible in developer tools is not detected by PHP for Safari. Same script is working fine in Chrome and Firefox.

Simplified example that illustrates the problem:

setcookie( 'cookiename', '1', time()+1200, '/' );

Reloading the page or loading other pages shows the cookie visible in the browser storage with the correct value in Safari. PHP on any page returns an empty $_COOKIE array but only in Safari.

var_dump( $_COOKIE );

array(0) {}

… in JS

document.cookie

I’ve read at least a dozen Safari cookie issues and solutions all over the web, including these:

$_COOKIE not working in Safari iOS

Not able to read cookie on JS side on Safari/iPhone

None appear to be relevant to the issue I’m facing.

TLDR: cookie is verified set correctly in Safari but PHP or JS to read it shows empty $_COOKIE array.

EDIT: suggested solution on the most similar problem I have found:
Use the assoc array options as detailed in docs: https://www.php.net/manual/en/function.setcookie.php

    setcookie( 'cookiename', '1', [
        'expires' => time()+1200,
        'path' => '/',
        'domain' => 'domain.com',
        'secure' => false,
        'httponly' => false,
        'samesite' => 'Lax',
        ]
    );

RESULT: Safari functioning as expected locally, but not on WPE server though the cookie is still visibly set but not read on subsequent page loads.