vscode-as3mxml: Can't debug the application

Followed the project setup step by step and created a very minimal project. When I start debugging I get the error:

Process terminated without establishing connection to debugger. application descriptor not found

Here is my launch.json:

{
    "version": "0.2.0",
    "configurations": [
        {
            "type": "swf",
            "request": "launch",
            "name": "Launch SWF",
            "profile": "mobileDevice",
            "screensize": "iPhoneRetina",
            "screenDPI": 326,
            "versionPlatform": "IOS"
        },
        {
            "type": "swf",
            "request": "attach",
            "name": "Attach SWF"
        }
    ]
}

I can see that VS Code can see the sdk from the lower right corner of the VSCode window.

EDIT: Building works fine using “ActionScript: compile debug build” task.