Error 11: There was a credentials issue

I have recieved yet another App Review rejection citing this error "Error 11: There was a credentials issue. Check the underlying error for more details."

Despite improvements I've made to the RevenueCat integration and testing myself using Sandbox accounts which work fine.

Can anyone help? I really need to release this app ASAP and am very stuck right now.

Thank you for your post. We're investigating your request currently. A representative from App Review will contact you to provide further assistance. If you continue to experience issues during review, please contact us.

Error 11: There was a credentials issue
 
 
Q