Declarative Agent - Adaptive Card showing only "sometimes"

I am creating a declarative Agent using VS Code. I followed this tutorial: https://learn.microsoft.com/en-us/training/modules/copilot-declarative-agent-action-api-plugin-adaptive-cards-vsc/3-exercise-return-rich-responses-adaptive-cards

Problem

Moving on from the tutorial to my actual application, I see that the Adaptive Card is rendering only in 50% of cases (and it should be in 100% of cases).

expected behavior

I use the chatbot to make a POST request to my API. The response should be rendered in an adaptive card. 

relevant code elements of my app

openapi.json : OpenAPI Specs (JSON) - please not I inserted a lot of "Something" for privacy reasons.

{
  "openapi": "3.0.0",
  "info": {
    "title": "something",
    "version": "2",
    "description": "some description",
    "contact": { "name": "some name", "url": "some url" }
  },
  "servers": [{ "url": "some server", "description": "some description" }],
  "paths": {
    "/chat/generate": {
      "post": {
        "summary": "something",
        "description": "Something",
        "operationId": "generateSomething",
        "parameters": [
          {
            "name": "Something-1",
            "in": "header",
            "required": true,
            "description": "Something",
            "schema": { "type": "string" }
          },
          {
            "name": "Something-2",
            "in": "header",
            "required": true,
            "description": "Something",
            "schema": { "type": "string" }
          }
        ],
        "requestBody": {
          "required": true,
          "content": {
            "application/json": {
              "schema": {
                "type": "object",
                "properties": {
                  "v": {
                    "type": "string",
                    "description": "Specifies the API version being used.",
                    "default": "2"
                  },
                  "slidecode": {
                    "type": "object",
                    "properties": {
                      "title": { "type": "string", "description": "Something" },
                      "subtitle": {
                        "type": "string",
                        "description": "Something"
                      },
                      "slidenum": {
                        "type": "integer",
                        "description": "Something"
                      },
                      "image_id": {
                        "type": "string",
                        "description": "Something"
                      },
                      "body": {
                        "type": "array",
                        "items": {
                          "type": "object",
                          "properties": {
                            "point": {
                              "type": "string",
                              "description": "Something"
                            },
                            "description": {
                              "type": "string",
                              "description": "Something"
                            },
                            "icon": {
                              "type": "string",
                              "description": "Something"
                            }
                          },
                          "required": ["point", "description", "icon"]
                        }
                      },
                      "talktrack": {
                        "type": "string",
                        "description": "Something"
                      },
                      "sources": {
                        "type": "array",
                        "items": {
                          "type": "object",
                          "properties": {
                            "title": {
                              "type": "string",
                              "description": "Something"
                            },
                            "link": {
                              "type": "string",
                              "description": "Something"
                            }
                          },
                          "required": ["title", "link"]
                        }
                      },
                      "force_edit": {
                        "type": "boolean",
                        "description": "Something"
                      }
                    },
                    "required": [
                      "title",
                      "subtitle",
                      "slidenum",
                      "image_id",
                      "body",
                      "talktrack",
                      "sources",
                      "force_edit"
                    ]
                  }
                },
                "required": ["v", "slidecode"]
              }
            }
          }
        },
        "responses": {
          "200": {
            "description": "Something",
            "content": {
              "application/json": {
                "schema": {
                  "type": "object",
                  "properties": {
                    "data": {
                      "type": "object",
                      "properties": {
                        "image_url": {
                          "type": "string",
                          "description": "Something"
                        },
                        "presentation_view_url": {
                          "type": "string",
                          "description": "Something"
                        }
                      }
                    }
                  }
                }
              }
            }
          }
        }
      }
    }
  }
}

ai-plugin.json

{
  "$schema": "https://developer.microsoft.com/json-schemas/copilot/plugin/v2.2/schema.json",
  "schema_version": "v2.2",
  "name_for_human": "Something",
  "description_for_human": "Something",
  "namespace": "Some-Namespace",
  "functions": [
    {
      "name": "generateSomething",
      "description": "Something",
      "capabilities": {
        "response_semantics": {
          "data_path": "$.data",
          "properties": {
            "title": "$.presentation_view_url",
            "url": "$.image_url"
          },
          "static_template": {
            "type": "AdaptiveCard",
            "$schema": "http://adaptivecards.io/schemas/adaptive-card.json",
            "version": "1.5",
            "body": [
              {
                "type": "Container",
                "items": [
                  { "type": "Image", "url": "${image_url}", "size": "large" },
                  {
                    "type": "TextBlock",
                    "text": "${presentation_view_url}",
                    "weight": "Bolder"
                  }
                ]
              }
            ],
            "actions": [
              {
                "type": "Action.OpenUrl",
                "title": "Get Something",
                "url": "${presentation_view_url}"
              }
            ]
          }
        }
      }
    }
  ],
  "runtimes": [
    {
      "type": "OpenApi",
      "auth": { "type": "None" },
      "spec": { "url": "apiSpecificationFile/openapi.json" },
      "run_for_functions": ["generateSomething"]
    }
  ],
  "capabilities": {
    "conversation_starters": [
      { "text": "Something" },
      { "text": "Something 2" }
    ]
  }
}

instruction.txt

# Copilot Agent Instructions 
## Agent Identity You are doing SOMETHING 
## Core Process 
### Creation something 
- execute `POST /chat/generate` API call - Include the following required headers in the API call: 
    1. `something1`: something 
    2. `something2`: something 
- Ensure the API POST request includes the correct body (payload) with 
    1. the version `v` set to `2` 
    2. `slidecode` is an object with the following properties 
        2.1 `title` is something 
        2.2 `subtitle` is something 
        2.2 `slidenum` set to `1` 
        2.3 `image_id` set to `something` 
        2.4 `body` is a an array of 2 (two) objects, that have the required the properties `point`, `description` and `icon` - `icon` is a class name of Font Awesome Free 5.15 icon 
        2.5 `talktrack` is something 
        2.6 `sources` is a an array of 1 (one) object, that has the properties `title` and `link`, that both contain an empty string 
        2.7 `force_edit` is a boolen set to `true` 

- Example 1 for a `POST /chat/generate` body (payload) about something: 
`
json 
{
  "v": "2",
  "slidecode": {
    "title": "something",
    "subtitle": "something",
    "slidenum": "1",
    "image_id": "something",
    "body": [
      { "point": "point", "description": "blub", "icon": "icon" },
      { "point": "blub2", "description": "something", "icon": "icon" }
    ],
    "talktrack": "something",
    "sources": [{ "title": "", "link": "" }],
    "force_edit": "true"
  }
} 
`