The current version of shopp when WordPress 3.7 was release is version 1.2.9. In some cases, the storefront catalog page does not display properly in WordPress 3.7. To fix this problem, the following snippet needs to be added to the functions.php file:
add_action('shopp_storefront_init', 'shopp_storefront_wp37_compat');
function shopp_storefront_wp37_compat() {
add_filter('archive_template', array(ShoppStorefront(), 'pages'));
}
Fix was provided by Barry on the Shopp support forums.