Im having the same problem, I added the billing method, verified the account. But its showing that PayPal charge failed.
My first payment went well then this problem appeared.
Could you solve this problem?
I checked your account and can see you have an old ticket for this issue. Please retry the transaction using an alternative payment method from your Paypal wallet, as the transaction did not complete with your selected payment method.
You may need to add an alternative payment method to your PayPal wallet in order to use your PayPal account as a payment method on Upwork.