"payment is a required field" in WC

I have a problem in the payment in WC shop.
plugins:
Active payments, Flexible Shipping PRO from WP Desk
On the payment page, after completing the client data and choosing the form of delivery and payment and pressing the button “buy and pay” I get message “payment is a required field” and I can not finish the order. This field is checked, I checked for each type of payment (bank transfer, payu, cash on delivery).
The guest shopping option is included.
There is no problem for logged users who created an account.
I turned off the plugs, still the same.
Any ideas?

Hello,

Can you please provide a link to your website?

Kind Regards, Roman.

http://chiomaroyal.pl/

Did you try to deactivate all your plugins except aThemes Toolbox and Page Builder by SiteOrigin, not just plugins that you mentioned above?

Kind Regards, Roman.

Yes, I tried but it did not help. I have turned off/on all plugins again, one by one and the problem appeared at the plugin cutsom checkout filds. I wrote to technical support. Thank You.

Okay, you can try to activate a default theme (for example Twenty Seventeen) and see if the issue persists.

It’s safer to do such things on a staging website, you might want to check this tutorial:

Kind Regards, Roman.