Appending main menu link deletes header meta menu?

Hello Enfold Team!

My site has a Header Meta bar at the top which displays some text on the left and the Secondary Menu on the right. The main menu is in the bar below that.

I am trying to append a Login/Logout link to the Main Menu, right before the Search icon. I have been able to do that with the code attached, but now the Secondary Menu is gone. Am I taking the right approach, and is there something wrong with the code or a conflict with the Priority 9996?

And where do we see a list of function Priorities?

Thanks for everything!

/* LOGIN MENU */
//first append search item to main menu
add_filter( 'wp_nav_menu_items', 'avia_append_login_menu', 9996, 2 );
add_filter( 'avf_fallback_menu_items', 'avia_append_login_menu', 9996, 2 );

function avia_append_login_menu ( $items, $args )
{	
	if(avia_get_option('header_position',  'header_top') != "header_top") return $items;

    if ((is_object($args) && $args->theme_location == 'avia') || (is_string($args) && $args = "fallback_menu"))
    {
        global $avia_config;
        ob_start();
                        
        if( is_user_logged_in() ) {
            $user = wp_get_current_user();
            $listclasses = "noMobile open-login menu-item menu-item-avia-special";
            $greeting = "Hi, ".esc_html($user->user_firstname)."!";
            $dashboardUrl = get_dashboard_url();
            $logoutUrl = wp_logout_url( home_url() );
            if( !current_user_can( 'administrator' ) && !is_admin() ) {
                $submenu = '<a>My Profile</a>';
            } else {
                $submenu = '<a href="'.$dashboardUrl.'">Dashboard</a>';
            }
            $logout = '<a href="'.$logoutUrl.'">Logout</a>';
            
            $loggedIn = <<<LOGGEDIN
                <li class="$listclasses $class">
                    <a href="#">
            			<span class="btn-text">
                            $greeting
                        </span>
                        <span class="btn-icon">
                            <span class="dashicons dashicons-admin-users"></span>
                        </span>
                    </a>
            		<ul class="sub-menu">
                        <li>
                            $submenu
                        </li>
                        <li>
                            $logout
                        </li>
                    </ul>
                </li>
LOGGEDIN;
        } else {
            $listclasses = "noMobile open-login lrm-login menu-item menu-item-avia-special";   
            $loggedOut = <<<LOGGEDOUT
            <li class="$listclasses $class">
                <a href="#">
        			<span class="btn-text">
                        Log In
                    </span>
                    <span class="btn-icon">
                        <span class="dashicons dashicons-admin-users"></span>
                    </span>
                </a>
            </li>
LOGGEDOUT;
        }
        if( is_user_logged_in() ) {
            $items .= $loggedIn;
        } else {
            $items .= $loggedOut;
        }
    return $items;
    }
}