Suitetalk api suiteql invalid login using php

Hi,

I'm attempting to use suiteql but am always getting a 401 INVALID_LOGIN response. I'm using exactly the same php code to generate the tokens etc that works successfully with GET calls to endpoints beneath /services/rest/record/v1 but does not work with POST calls to /services/rest/query/v1/suiteql

My code looks like this:-

$fullUrl = "$NS_API_BASE_URL/services/rest/query/v1/suiteql";

$httpMethod     = 'PUT';

$signatureMethod = 'HMAC-SHA256';

$nonce          = substr(str_shuffle("0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"), 0, 20);

$timestamp      = time();

$version        = '1.0';

$query = [

   "q" => "select * from customer"

];

$baseString = oauth_get_sbs($httpMethod, $fullUrl, array(

                              'oauth_consumer_key' => $NS_CLIENT_ID,