VS Code not showing Typescript errors inline

I am confused why my VSCode isn't showing any Typescript errors.

When I run tsc in the terminal then I do see the errors showing, but these are not in my files inline.

My current setup

tsconfig.json

{
  "compilerOptions": {
    "target": "es5",
    "allowJs": true,
    "esModuleInterop": true,
    "allowSyntheticDefaultImports": true,
    "strict": true,
    "forceConsistentCasingInFileNames": true,
    "module": "esnext",
    "moduleResolution": "node",
    "resolveJsonModule": true,
    "isolatedModules": true,
    "noEmit": true,
    "jsx": "preserve",
    "lib": [
      "es2015",
      "dom"
    ],
    "skipLibCheck": false
  },
  "include": [
    "src"
  ]
}

index.ts - Expected error thrown but not

const a: number = 'test';

I have also updated the settings in VS to add the following as per the advice from this link, but still not showing any errors.

https://stackoverflow.com/a/53134524/3284707