WordPress: Applying new query_vars in theme functions to create conditional menu

Within my child-theme function file, I have:

– Registered a custom menu location ‘link-arch-nav’,
– Added a filter and rewrite rule to grab two variables from the URL structure called ‘linkarchpostyear’ and ‘linkarchpostmonth’,

– **Lastly, I’m trying to apply those two variables into my custom menu links but I can’t figure out how to apply the newly created variables into my menu_override function.**

My relative code *(all within my child-theme’s functions.php file, in order of appearance)*:

———-

/*
    ** Add URL path for custom page template into query string
    */
    add_action( 'init', 'linkarchivepost_permalinks' );

    function linkarchivepost_permalinks() {
    add_rewrite_rule(
        'archives/([^/]+)/([^/]+)/?',
        'index.php?pagename=archives&linkarchpostyear=$matches[1]&linkarchpostmonth=$matches[2]',
        'top'
    );
    }
    add_filter( 'query_vars', 'linkarchivepost_query_vars' );
    function linkarchivepost_query_vars( $query_vars ) {
        $query_vars[] = 'linkarchpostyear';
	    $query_vars[] = 'linkarchpostmonth';
        return $query_vars;
    }

    /*
    ** Generate menu link URL variables with format '--variable--' utilizing the above query_vars URL structure variables.
    */
    add_filter( 'nav_menu_link_attributes', 'arch_menu_override', 10, 3 );

    function arch_menu_override( $atts, $item, $args ) {
	    $searchpostyear = $wp_query->query_vars['linkarchpostyear'];
	    $searchpostmonth = $wp_query->query_vars['linkarchpostmonth'];

        $testarchlink = $searchpostyear . '/' . $searchpostmonth;
        $newlink = str_replace("--archivedate--", $testarchlink, $atts[href]);
        $atts[href] = $newlink;
        return $atts;
    }

———-

With this code, it seems as though the menu link attachments and variable replacement code for the menu URLs is working but the $wp_query->query_vars variables are not carrying over. Instead, I end up with a URL that looks like this: “/archives///”.

This is telling me that everything is working except that the new URL variables are blank. To make sure, I assigned values to $searchpostyear and $searchpostmonth within the menu override function and got this menu URL: “/archives/test1/test2/”

Any help hooking/correcting the variable calls correctly would be amazing!