This error Failed to query employee [EMPLOYEE EMAIL] because the credentials are invalid means that either the Bob app in the NetSuite instance got removed or its role with its associated user were modified in NetSuite or any additional changes were made to the integration part in NetSuite (NS). Please go through the setup guide precisely with checking every setting you see in NetSuite now.
When you see the error like shown above + NS fields are not retrieved. It means the setup part in NetSuite was modified, not as per the guide:
