MessageCard Action input title does not appear

Question

I have a MessageCard I send to Teams via incoming webhook which includes an action with a couple of inputs.

Problem is the first input does not show the title:

Here is the JSON I am sending:

{
  "@type": "MessageCard",
  "@context": "https://schema.org/extensions",
  "summary": "Summary",
  "title": "Title",
  "text": "Truncated",
  "potentialAction": [
    {
      "@type": "ActionCard",
      "name": "Retry failed tests",
      "inputs": [
        {
          "@type": "MultichoiceInput",
          "choices": [
            {
              "display": "prod.eu.qeautomation-01",
              "value": "prod.eu.qeautomation-01"
            },
            {
              "display": "prod.eu.qeautomation-02",
              "value": "prod.eu.qeautomation-02"
            },
            {
              "display": "prod.eu.qeautomation-03",
              "value": "prod.eu.qeautomation-03"
            },
            {
              "display": "prod.eu.qeautomation-04",
              "value": "prod.eu.qeautomation-04"
            },
            {
              "display": "prod.eu.qeautomation-05",
              "value": "prod.eu.qeautomation-05"
            },
            {
              "display": "prod.eu.qeautomation-06",
              "value": "prod.eu.qeautomation-06"
            },
            {
              "display": "prod.us.qeautomation-04",
              "value": "prod.us.qeautomation-04"
            },
            {
              "display": "prod.us.qeautomation-05",
              "value": "prod.us.qeautomation-05"
            },
            {
              "display": "prod.us.qeautomation-06",
              "value": "prod.us.qeautomation-06"
            },
            {
              "display": "prod.us.qeautomation-07",
              "value": "prod.us.qeautomation-07"
            },
            {
              "display": "prod.us.qeautomation-08",
              "value": "prod.us.qeautomation-08"
            },
            {
              "display": "shadow.us.qeautomation-01",
              "value": "shadow.us.qeautomation-01"
            },
            {
              "display": "shadow.us.qeautomation-02",
              "value": "shadow.us.qeautomation-02"
            },
            {
              "display": "shadow.us.qeautomation-03",
              "value": "shadow.us.qeautomation-03"
            },
            {
              "display": "shadow.us.qeautomation-04",
              "value": "shadow.us.qeautomation-04"
            },
            {
              "display": "shadow.us.qeautomation-05",
              "value": "shadow.us.qeautomation-05"
            },
            {
              "display": "shadow.us.qeautomation-06",
              "value": "shadow.us.qeautomation-06"
            },
            {
              "display": "shadow.us.qeautomation-07",
              "value": "shadow.us.qeautomation-07"
            }
          ],
          "id": "account",
          "isRequired": true,
          "title": "Account",
          "value": "shadow.us.qeautomation-05"
        },
        {
          "@type": "MultichoiceInput",
          "choices": [
            {
              "display": "Include",
              "value": "Include"
            },
            {
              "display": "Exclude",
              "value": "Exclude"
            },
            {
              "display": "Run only serial tests",
              "value": "Run only serial tests"
            }
          ],
          "id": "serial_tests",
          "isRequired": true,
          "style": "expanded",
          "title": "Serial tests",
          "value": "Include"
        }
      ],
      "actions": [
        {
          "@type": "HttpPOST",
          "name": "Retry failed tests",
          "body": "ignore",
          "target": "https://ignore.me"
        }
      ]
    }
  ]
}