Paypal: Client Authentication Failed

Trying to take my paypal REST api site live. It works well in sandbox mode, with verified transfers.

When I switch my sandbox for live client ID and secret, I get the error

{"error":"invalid_client","error_description":"Client Authentication failed"}   

I checked and made sure that my code should go live

$apiContext = new \PayPal\Rest\ApiContext( new \PayPal\Auth\OAuthTokenCredential(  PP_CLIENT_ID ,     // ClientID  PP_CLIENT_SECRET      // ClientSecret ));// setting mode to live// https://github.com/paypal/PayPal-PHP-SDK/wiki/Going-Live$apiContext->setConfig(['mode' => 'live',]);

running this via wp_ajax

Any help would be appreciated! Thanks!

2/5/2019: Seems other people got this problem: https://github.com/paypal/PayPal-PHP-SDK/issues/435

Also the same question on StackOverflow that I missed ... that also had no answer.PayPal App works perfectly as Sandbox, Client Authentication failed on Live: list of steps to check?