Coinbase Commerce Woocommerce Error response from API: Required parameter missing: pricing_type

Question

Integrated Coinbase Commerce to my Wordpress Woocommerce website and everything was working just fine since yesterday. When customer click on "Proceed to Coinbase" button to finish a purchase, website says "Error processing checkout. Please try again."

I logged Coinbase Commerce Plugin and I can see that error is:

2018-09-25T10:57:06+00:00 INFO Coinbase Request Args for charges: Array
(
    [name] => DomainName
    [description] => some description
    [pricing_type] => fixed_price
    [local_price] => Array
        (
            [amount] => 3000.00
            [currency] => USD
        )

    [metadata] => Array
        (
            [order_id] => 438
            [order_key] => wc_order_5ba994a3a976c
        )

    [redirect_url] => https://example.com/checkout/order-received/438/?key=wc_order_5ba994a3a976c
)

2018-09-25T10:57:07+00:00 INFO Error response from API: Required parameter missing: pricing_type

I don't know what to do, what do I need to change to fix that..