Multisite CSS Stylesheet for plugin

I’m using Multisite and the Multisite Global Search plugin (Network activated with appropriate search pages set up on each site)

Multisite Global Search plugin has a style.css in the folder Multisite Global Search under my plugins directory.

Multisite Global Search has this code which sets where the CSS is:

/**
 * Add style file if it exists.
 */
function ms_global_search_style() {
	$styleurl = MSGLOBALSEARCH_URL . '/style.css';
	$styledir = MSGLOBALSEARCH_DIR . '/style.css';

	if( file_exists( $styledir ) )
		wp_enqueue_style( 'ms_global_search_css_style', $styleurl );
}

When I make changes to the style sheet, I see the changes for the main parent site, but not for the other sites.

Is there something different I need to be doing for those other sites to recognize that style sheet for Multisite Global Search?

Thanks,
Coleen