How can I handle additional user replies in an n8n workflow with Meta's WhatsApp API?

I’m unable to capture a follow-up message in my n8n workflow using Meta WhatsApp API—only the initial reply registers.

[
  {
    "platform": "WA",
    "userDetails": { "inputText": "", "identifier": "" },
    "replyData": [{ "ref": "newID_456" }]
  }
]