PHP Mailchimp API v3 , passing arguments other than fields ignored

Question

I cannot get the mailchimp api to return more than 10 items or "see" any query parameters. The documentation lists the query parameters allowed but never shows an example, in php.

    //boilerplate
    $client = new MailchimpMarketing\ApiClient();
    $client->setConfig([
        'apiKey' => 'YOUR_API_KEY',
        'server' => 'YOUR_SERVER_PREFIX',
    ]);
    $client->lists->getListMembersInfo('xx_list_id_xxx', 
["fields" => 'members.email_address,members.status,members.full_name,members.ip_signup,members.location.latitude,members.location.longitude,members.location.country_code',
"count" => 300]);

The above does not work as expected, but if I remove the 'count' entry it does.

I have also tried the named argument format is follows:

$client->lists->getListMembersInfo($list_id='xxxxx', $fields='members.email_address,members.status,members.full_name', $count=20);

Does anyone have any experience with the php mailchimp api that can give me some examples of how to send the query parameters?

PS: ping works fine, and my API_KEY and SERVER are correct