CEP Extension no longer working InDesign 18.2.1 - VS Code Debugger config

I have a plugin built in CEP 9 that has stopped working with 18.2.1.

The plugin no longer loads at all and I'm struggling to get a development version up and running to debug it.

The VS Code Debugger is new since I last touched CEP and I'm not sure that I'm configuring it correctly.

I have created a launch.json file and configured a compound launch request as below:

  "version": "0.2.0",
  "configurations": [
    {
      "type": "chrome",
      "request": "attach",
      "name": "[Attach] CEP JavaScript",
      "port": 8090, // <-- Whatever debug port you have configured.
      "webRoot": "${workspaceRoot}/index.html",
      "pathMapping": {
        "/": "${workspaceRoot}/js/main.js"
      }
    },
    {
      "type": "extendscript-debug",
      "request": "attach",
      "name": "[Attach] CEP ExtendScript",
      "hostAppSpecifier": "indesign-18"
    }
  ],
  "compounds": [
    {
      "name": "[Compound] Debug CEP",
      "configurations": [
        "[Attach] CEP JavaScript",
        "[Attach] CEP ExtendScript"
      ]
    }
  ]
}

When I attempt to launch the extension the debugger returns the error:

"Cannot connect to the target at localhost:8090: Could not connect to debug target at http://localhost:8090: Could not find any debuggable target"

I'm a bit stumped as how to proceed if I'm honest; I've been using UXP for the last few years and have kinda forgotten CEP's idiosyncrasities.