DB table is not created correctly in multisite environment

Hi,
I’m using your beautiful plugin, but I found that this plugin does not work well in multisite environment.
It seems that the main site is OK, but in sub sites, tables wp_n_terms_hit are not created when I activate this plugin using “Network Activate” in Network Admin.

Could you check with the code below?

class.database.php: line 28

// not tested
if (is_multisite()) {
    $sites = get_sites();
    foreach($sites as $site) {
        switch_to_blog( $site['blog_id'] );
        $is_table = self::is_table_exists();
        if ( empty( $is_table ) ) {
            self::create_table();
        }
        restore_current_blog();
    }
} else {
    $is_table = self::is_table_exists();
    if ( empty( $is_table ) ) {
        self::create_table();
    }
}

Thanks.