title: Stripe one time payments allow promotion code
body: <p>I am going to implement a promotion code with a one-time payment. Stripe has announcement to use &quot;allow_promotion_code=true&quot; parameter on one time payments.</p>
  <p>But something wrong with promotion input. Sometimes promotion code input didn't show up. Is there a bug for stripe or did I miss something?</p>
  <pre class="lang-json prettyprint-override"><code>
    &quot;id&quot;: &quot;cs_test_b1IjCh7A8FGNDekAWtQZR93USCT2G3dxRe9zyLcGg7Qy3Ddt8yxxxx&quot;,
    &quot;object&quot;: &quot;checkout.session&quot;,
    &quot;allow_promotion_codes&quot;: true,
    &quot;amount_subtotal&quot;: 4140,
    &quot;amount_total&quot;: 4140,
    &quot;billing_address_collection&quot;: &quot;required&quot;,
    &quot;cancel_url&quot;: &quot;http://localhost:8000/checkout?session_id={CHECKOUT_SESSION_ID}&quot;,
    &quot;client_reference_id&quot;: null,
    &quot;currency&quot;: &quot;gbp&quot;,
    &quot;customer&quot;: null,
    &quot;customer_email&quot;: null,
    &quot;livemode&quot;: false,
    &quot;locale&quot;: null,
    &quot;metadata&quot;: {
    },
    &quot;mode&quot;: &quot;payment&quot;,
    &quot;payment_intent&quot;: &quot;pi_1HxdH1CZvxxxxxx&quot;,
    &quot;payment_method_types&quot;: [
      &quot;card&quot;
    ],
    &quot;payment_status&quot;: &quot;unpaid&quot;,
    &quot;setup_intent&quot;: null,
    &quot;shipping&quot;: null,
  </code></pre>