The assets/scss should NOT be created, as the content is compiled into css/app.css (so in the css directory).
This is something new, we didn't see that behavior when building old sites.
$ tree tests/site/dist tests/site/dist ├── assets │ ├── css │ │ └── app.css │ ├── img │ ├── js │ │ ├── app.js │ │ ├── app.js.LICENSE.txt │ │ └── lib │ └── scss │ ├── components │ └── global └── index.html