Some orders not updated on payment, other orders not detecting payment

The past two days I've detected unwanted behaviours on three orders (out of approximately 25). I'm using WPS

My checkout rules are based on the 'When order is payed in full'-action, not checkout completion.

2 orders were paid, and the payment is visible on the order, but the order wasn't updated to pending status (in stead stuck in checkout:complete). Besides having to change state myself it also stopped my order notifications from going out to the customers.

1 order were paid and the payment wasn't registered at all - leaving the order in the checkout:payment status

Here's my WPS rule:

{ "commerce_payment_paypal_wps" : {
    "LABEL" : "PayPal WPS",
    "PLUGIN" : "reaction rule",
    "OWNER" : "rules",
    "TAGS" : [ "Commerce Payment" ],
    "REQUIRES" : [ "commerce_payment" ],
    "ON" : { "commerce_payment_methods" : [] },
    "DO" : [
      { "commerce_payment_enable_paypal_wps" : {
          "commerce_order" : [ "commerce-order" ],
          "payment_method" : { "value" : {
              "method_id" : "paypal_wps",
              "settings" : {
                "business" : "info@tambourhinoceros.net",
                "currency_code" : "DKK",
                "allow_supported_currencies" : 0,
                "language" : "US",
                "server" : "live",
                "payment_action" : "sale",
                "ipn_logging" : "notification",
                "receiver_emails" : "info@tambourhinoceros.net",
                "ipn_create_billing_profile" : 0,
                "show_payment_instructions" : 1
              }
            }
          }
        }
      }
    ]
  }
}

Here's my order status update rule:

{ "commerce_checkout_order_status_update" : {
    "LABEL" : "Update the order status on full payment",
    "PLUGIN" : "reaction rule",
    "OWNER" : "rules",
    "TAGS" : [ "Commerce Checkout" ],
    "REQUIRES" : [ "commerce_order", "commerce_payment" ],
    "ON" : { "commerce_payment_order_paid_in_full" : [] },
    "DO" : [
      { "commerce_order_update_state" : { "commerce_order" : [ "commerce-order" ], "order_state" : "pending" } }
    ]
  }
}

And finally my order notification rule;

{ "rules_commerce_order_message_order_notification" : {
    "LABEL" : "Commerce order message: order notification e-mail",
    "PLUGIN" : "reaction rule",
    "WEIGHT" : "3",
    "OWNER" : "rules",
    "REQUIRES" : [ "rules", "message_notify", "commerce_payment" ],
    "ON" : { "commerce_payment_order_paid_in_full" : [] },
    "DO" : [
      { "entity_create" : {
          "USING" : {
            "type" : "message",
            "param_type" : "commerce_order_order_confirmation",
            "param_user" : [ "commerce-order:owner" ]
          },
          "PROVIDE" : { "entity_created" : { "entity_created" : "Created entity" } }
        }
      },
      { "data_set" : {
          "data" : [ "entity-created:message-commerce-order" ],
          "value" : [ "commerce-order" ]
        }
      },
      { "entity_save" : { "data" : [ "entity-created" ], "immediate" : 1 } },
      { "message_notify_process" : {
          "message" : [ "entity-created" ],
          "save_on_fail" : 0,
          "save_on_success" : 0
        }
      }
    ]
  }
}

What can be causing these errors?