I have found a bug in the admin section that all active payment methods are not loading, it loads only default Magento 2 enabled Payment Methods.
After overriding and edit file Model/System/Config/Source/PaymentMethods.php and write below code
/**
* @param ScopeConfigInterface $appConfigScopeConfigInterface
* @param Config $paymentModelConfig
*/
public function __construct(
ScopeConfigInterface $appConfigScopeConfigInterface,
Config $paymentModelConfig
) {
$this->_appConfigScopeConfigInterface = $appConfigScopeConfigInterface;
$this->_paymentModelConfig = $paymentModelConfig;
}
public function toOptionArray()
{
$payments = $this->_paymentModelConfig->getActiveMethods();
$methods = array();
$methods = [['label' => __('-- Please select --'), 'value' => '']];
foreach ($payments as $paymentCode => $paymentModel) {
$paymentTitle = $this->_appConfigScopeConfigInterface
->getValue('payment/'.$paymentCode.'/title');
$methods[$paymentCode] = array(
'label' => $paymentTitle,
'value' => $paymentCode
);
}
return $methods;
}
Please resolve issue and upgrade your module.