mpbm23

I already am using it

This is not my plugin. I am just helping with support and troubleshooting.
Make the change and I will contact the author to push the update.

Replace line 117 with

$chosen_methods[]=null;

Replace line 117 with

$chosen_methods[]=null;

Please replace

add_action( 'woocommerce_init' , array( &$this , 'add_payment_options'), 99 );

with

add_action( 'wp_loaded' , array( &$this , 'add_payment_options'), 99 );

as seen here
https://github.com/mcguffin/woocommerce-payforpayment/blob/master/admin/class-pay4pay-admin.php
In file /admin/class-pay4pay-admin.php

Please replace

add_action( 'woocommerce_init' , array( &$this , 'add_payment_options'), 99 );

with

add_action( 'wp_loaded' , array( &$this , 'add_payment_options'), 99 );

as seen here
https://github.com/mcguffin/woocommerce-payforpayment/blob/master/admin/class-pay4pay-admin.php
In file /admin/class-pay4pay-admin.php

Please replace

add_action( 'woocommerce_init' , array( &$this , 'add_payment_options'), 99 );

with

add_action( 'wp_loaded' , array( &$this , 'add_payment_options'), 99 );

as seen here
https://github.com/mcguffin/woocommerce-payforpayment/blob/master/admin/class-pay4pay-admin.php

I believe wp_loaded instead of woocommerce_init did the trick.
Thanks for the help

I have reduced it to to files with minimal code and the results are the same.

class Pay4Pay {
	private static $_instance = null;
	public static function instance(){
		if ( is_null(self::$_instance) )
			self::$_instance = new self();
		return self::$_instance;
	}

	private function __construct() {
	}
}
Pay4Pay::instance();
if ( is_admin() )
	require_once plugin_dir_path(__FILE__) . '/admin/class-pay4pay-admin.php';

Admin file

if ( ! class_exists( 'Pay4Pay_Admin' ) ) :

class Pay4Pay_Admin {

	private static $_instance = null;

	public static function instance(){
		if ( is_null(self::$_instance) )
			self::$_instance = new self();
		return self::$_instance;
	}

	private function __construct() {
		// handle options
		add_action( 'woocommerce_init' , array( &$this , 'add_payment_options'), 99 );
		add_action( 'woocommerce_update_options_checkout' , array( &$this , 'add_payment_options') );

	}

	function add_payment_options( ) {
	var_dump(WC()->payment_gateways()->payment_gateways() );
	}

}

Pay4Pay_Admin::instance();

endif;

Mike Jolley I have narrowed it down to a single call of available gateways
specifically to this line
foreach ( WC()->payment_gateways()->payment_gateways() as $gateway_id => $gateway ) {
Its line 200 in https://github.com/mcguffin/woocommerce-payforpayment/blob/master/admin/class-pay4pay-admin.php

But I can not understand why its interfering with the shipping methods.
I tried replacing it with $woocommerce->payment_gateways()->payment_gateways() but it makes no difference.
I am not the author of pay4payment, just trying to help.

I really don’t know how a payment plugin can interfere with a shipping plugin.

Yes I can also confirm the problem.
The thing is, pay for payment is used for payment gateways and not shipping methods. Can not understand how it can create a problem.

Please contact Woocart Pro by Festi support team to help you.

What shipping method are you using?

Where you using https://www.ads-software.com/plugins/woocommerce-pay-for-payment/ for setting price in your payment gateways?
I am using 2.4 but do not have any issue saving.
What shipping method are you using?