TypeScript: Compile on Build / Compile on Save problems with TS 1.8 in Visual Studio 2015

Since I installed TS 1.8 I’ve started noticing that the compile step is not being executed in Visual Studio either on save or upon build when there are existing *.js files in place.

So if I’m working on viewModel.ts then I need to delete viewModel.js and trigger a Visual Studio build in order that a new viewModel.js is created.

My tsconfig.json looks like this:

{
  "compileOnSave": false,
  "compilerOptions": {
    "inlineSourceMap": true,
    "inlineSources": true,
    "noEmitOnError": true,
    "noImplicitAny": true,
    "preserveConstEnums": true,
    "removeComments": false,
    "sourceMap": false,
    "target": "es5"
  },
  "filesGlob": [
    "**/*.ts"
  ],
  "files": [
    // lots of files here - excluded for brevity
  ],
  "atom": {
    "rewriteTsconfig": true
  }
}

I wondered if it might be related to presence of the compileOnSave flag in tsconfig.json (which I believe is supported as of TS 1.8?). However setting it to true and removing it entirely made no discernible differerence to behaviour. (I tried closing and reopening the project in between changes in case there were caching issues but no change.)

So compileOnSave seems entirely broken (i.e. it never compiles on save) and compile on build only works if the existing js files are deleted.