Inlining css breaks urls with non standard ports

When I’m running locally or in some of my client’s staging environments, enabling the option to “Inline CSS Files” breaks various URLs within those files.

This seems to happen only when the site URL includes a port number.

For example, when running on port 444 the following CSS…

src:url(../webfonts/fa-solid-900.eot);

… becomes …

src:url(:444/wp-content/plugins/elementor/assets/lib/font-awesome/css/:444/wp-content/plugins/elementor/assets/lib/font-awesome/css/../webfonts/fa-solid-900.eot);