additionalStreams not working

Given the below code, which I've simplified to make more readable:

gulp.task('build', function() {
  var templateStream = gulp.src('src/**/!(index).html')
    .pipe(processTemplates()) // lazypipe that just calls gulp-angular-templatecache.

  return gulp.src('src/index.html')
    .pipe(addTemplateToIndex()) // Adds <script> reference to 'app/app.templates.js'.
    .pipe($.useref({
      additionalStreams: [templateStream]
    }))
    .pipe($.if('app/**/*.js', processOwnJs()))
    .pipe($.if('*.js', processAllJs()))
    .pipe($.if('*.html', processAllHtml()))
    .pipe(gulp.dest('dist'));
});

I'm getting a File not found with singular glob error, specifying the full absolute path of the 'app/app.templates.js' file.

I can't seem to figure out what exactly is going wrong; through inserting a few calls to gulp-debug I can see that the app.templates.js file appears to be getting passed along with the expected cwd, base and path properties.