--watch does not watch if given a .css source file

[EricBanker12]

The issue

Sass watcher will not detect changes if given a .css source file. If the output file does not exist or differs to the compiled source, it will be compiled immediately after running the command, but further changes to the source file will not trigger new compiles. When using a .scss source file, further changes do trigger new compiles as expected.

Examples

with .css source file:

sass --watch --style=compressed test.css test.min.css
Compiled test.css to test.min.css.
Sass is watching for changes. Press Ctrl-C to stop.

with .scss source file:

sass --watch --style=compressed test.scss test.min.css
Compiled test.scss to test.min.css.
Sass is watching for changes. Press Ctrl-C to stop.

Compiled test.scss to test.min.css.

In both examples, the initial content of test.css and test.scss is:

.test {
    font-family: 'Hello World!';
}

Changes were induced by altering the Hello World! string and saving.

Setup

OS: Windows 10
Command Line: Git Bash (2.22.0.windows.1) with mintty (3.0.2) terminal
Sass installation: npm i --global sass
Sass version: 1.22.10 compiled with dart2js 2.4.1