WPBakery/Visual Composer back-end custom CSS not working

Question

I'm trying to make the text darker in various editors (HTML, javascript, etc)... According to WPBakery documentation, I should be able to do this in the WPBakery->Settings->Custom CSS tab. It says "Add custom CSS code to the plugin without modifying files."

So I add the CSS, which I tested in the browser Developer tools:

.vc_edit_form_elements .textarea_raw_html, .wpb_element_wrapper .textarea_raw_html {
    font-family: "Courier New";
    color: #333;
    font-size: 11px;
    word-break: break-all;
}

However, the change does not happen after I save it on WPBakery. The CSS still shows on the Custom CSS tab, but no change to the editor text color.

I've tried both with Design Options->Use Custom Design Options checked and not checked. No luck. Any idea how to fix it without actually editing the plugin style sheet?