Trouble adding custom stylesheet

For all StudioPress themes, I add a custom functions.php and a custom stylesheet. For Aspire, the code to add the custom child theme caused the body of pages, except the home page, to not show. I just get the header (logo and menu). When I delete the code for the custom stylesheet, the pages show properly but without my custom styles. Here is the code that I add to the functions file:

//* Add custom stylesheet
add_action( 'wp_head', 'add_custom_stylesheet' );
function add_custom_stylesheet() {
    $customStylesheet=get_bloginfo( 'stylesheet_directory' ).'/style_custom.css';
   echo '<link rel="stylesheet" type="text/css" href="' . $customStylesheet . '" media="all">';
} 

This worked before with the theme version 1.0 but not with the current version. Here is the URL where the content does not show.

https://islandrunnervi.com/contact-us/

Any help, would be great. Thanks.