Problem soved for 'free shipping' shopping cart scenario:
Head to wooCommerce > Settings > Shipping.
Ensure you have 'free shipping' radio button selected.
Select "Free Shipping" from the text menu item at the top.
Select "N/A" from the "Free Shipping Requires..." drop down.
Whilst in this area, click on "Payment Gateways" tab. then select PayPal text menu. Ensure you don't have 'Enable PayPal Sandbox' selected.
Test checkout.
Hope this helps.