Request article processing charges in ojs

Hi all!
There was a problem with request article processing charges by the author using paypal.

The plugin is configured for the sandbox (for now), but I don’t see the “Request for payment” button like this Subscriptions
Also, we tried with a business account too.

PHP error log is empty

In production, I see only: Payment Received and Waive

Version OJS
PHP version 7.4.5




What did I do wrong? What did I miss?
Thank you!

The problem is still relevant …