PayPal RESTful API Payment Module

[siliconbug]

Zen Cart v1.58a
Paypal RESTful v1.0.2
Payment Action: Auth Only

I disable PayPal Express Checkout and enable Paypal RESTful today.

There are two orders. The 1st order is paid by PayPal Wallet, and the 2nd order is paid by Credit Card.

The 1st payment goes through, but the 2nd order gives me an error:


Both orders get this error when I capture the payments, but I can get correct $$ into my PayPal account:



Something under PayPal Transactions doesn't look right.

Attachment 20651

Should I remove PayPal Express Checkout completely? Or any possible issue I missed?

I disable Credit Card and keep using PayPal Wallet only.
Still get the same error after every order:

The payment module's observer (auto.paypalrestful.php) was not loaded; the payment module has been disabled. The payment module has been automatically disabled.

Logs don't show any error, and I can capture $$ without any issue.
/includes/classes/observers/auto.paypalrestful.php is at the right place.
I test it in Sandbox mode, and everything goes well without such an error.

Is there anything I miss?