/**
 * CORREÇÃO SEGURA: Força o campo 'wcfmmp_shipping_type' a ser um 'multi-checkbox' 
 * para permitir a seleção múltipla, sem injeção manual de HTML/JS que causou erro.
 */
function custom_wcfmmp_force_multicheckbox( $shipping_fields ) {
    
    // 1. Verifica se o campo 'wcfmmp_shipping_type' existe
    if ( isset( $shipping_fields['wcfmmp_shipping_type'] ) ) {
        
        // 2. Altera o tipo de campo para o tipo de formulário correto do WCFM
        $shipping_fields['wcfmmp_shipping_type']['type'] = 'multi-checkbox';
        
        // 3. Define as classes CSS corretas para 'multi-checkbox' e para o JS do WCFM
        $shipping_fields['wcfmmp_shipping_type']['class'] = 'wcfm-checkbox wcfm_ele hide_if_shipping_disabled';
        $shipping_fields['wcfmmp_shipping_type']['label_class'] = 'wcfm_title checkbox_title wcfm_ele hide_if_shipping_disabled';
        
        // 4. Garante que o valor inicial seja um array (necessário para multi-select/checkbox)
        if ( isset( $shipping_fields['wcfmmp_shipping_type']['value'] ) && !is_array( $shipping_fields['wcfmmp_shipping_type']['value'] ) ) {
            $shipping_fields['wcfmmp_shipping_type']['value'] = array( $shipping_fields['wcfmmp_shipping_type']['value'] );
        }
    }
    
    return $shipping_fields;
}
add_filter( 'wcfmmp_settings_fields_shipping', 'custom_wcfmmp_force_multicheckbox', 50 );
<title>XML Sitemap</title><style type="text/css">
					body {
						font-family:"Lucida Grande","Lucida Sans Unicode",Tahoma,Verdana;
						font-size:13px;
					}
					
					#intro {
						background-color:#cfebf7;
						border:1px #2580B2 solid;
						padding:5px 13px 5px 13px;
						margin:10px;
					}
					
					#intro p {
						line-height:16.8667px;
					}
					#intro strong {
						font-weight:normal;
					}
					
					td {
						font-size:11px;
					}
					
					th {
						text-align:left;
						padding-right:30px;
						font-size:11px;
					}
					
					tr.high {
						background-color:whitesmoke;
					}
					
					#footer {
						padding:2px;
						margin-top:10px;
						font-size:8pt;
						color:gray;
					}
					
					#footer a {
						color:gray;
					}
					
					a {
						color:black;
					}
				</style><h1>XML Sitemap Index</h1><div id="intro"><p>
                This XML sitemap is used by search engines which follow the <a rel="external nofollow" href="https://sitemaps.org">XML sitemap standard</a>. This file contains links to sub-sitemaps, follow them to see the actual sitemap content.
            </p><p>
                This file was dynamically generated using the <a rel="external nofollow" href="https://wordpress.org/">WordPress</a> content management system and <strong><a rel="external nofollow" href="https://auctollo.com/products/google-xml-sitemap-generator/" title="XML Sitemap Generator for Google">XML Sitemap Generator for Google</a></strong> by <a rel="external nofollow" href="https://auctollo.com/">Auctollo</a>.
            </p></div><div id="content"><table><tr style="border-bottom:1px black solid"><th>URL of sub-sitemap</th><th>Last modified (GMT)</th></tr><tr><td><a href="https://uptay.com.br/sitemap-misc.html">https://uptay.com.br/sitemap-misc.html</a></td><td>2025-11-11T02:41:38+00:00</td></tr><tr class="high"><td><a href="https://uptay.com.br/post_tag-sitemap.html">https://uptay.com.br/post_tag-sitemap.html</a></td><td>2025-11-11T02:41:38+00:00</td></tr><tr><td><a href="https://uptay.com.br/category-sitemap.html">https://uptay.com.br/category-sitemap.html</a></td><td>2025-11-11T02:41:38+00:00</td></tr><tr class="high"><td><a href="https://uptay.com.br/producttags-sitemap.html">https://uptay.com.br/producttags-sitemap.html</a></td><td>2025-11-11T02:41:38+00:00</td></tr><tr><td><a href="https://uptay.com.br/producttags-sitemap2.html">https://uptay.com.br/producttags-sitemap2.html</a></td><td>2025-11-11T02:41:38+00:00</td></tr><tr class="high"><td><a href="https://uptay.com.br/productcat-sitemap.html">https://uptay.com.br/productcat-sitemap.html</a></td><td>2025-11-11T02:41:38+00:00</td></tr><tr><td><a href="https://uptay.com.br/product-sitemap.html">https://uptay.com.br/product-sitemap.html</a></td><td>2025-11-09T21:21:36+00:00</td></tr><tr class="high"><td><a href="https://uptay.com.br/post-sitemap.html">https://uptay.com.br/post-sitemap.html</a></td><td>2024-09-24T04:07:38+00:00</td></tr><tr><td><a href="https://uptay.com.br/page-sitemap.html">https://uptay.com.br/page-sitemap.html</a></td><td>2025-11-11T02:41:38+00:00</td></tr><tr class="high"><td><a href="https://uptay.com.br/archives-sitemap.html">https://uptay.com.br/archives-sitemap.html</a></td><td>2025-11-11T02:41:38+00:00</td></tr></table></div><div id="footer"><p>
						Dynamically generated with <a rel="external nofollow" href="https://auctollo.com/products/google-xml-sitemap-generator/" title="XML Sitemap Generator for Google">XML Sitemap Generator for Google</a> by <a rel="external nofollow" href="https://auctollo.com/">Auctollo</a>. This XSLT template is released under the GPL and free to use.
            		</p><p>
	                    If you have problems with your sitemap please visit the <a rel="external nofollow" href="https://auctollo.com/products/google-xml-sitemap-generator/help/" title="Frequently Asked Questions">FAQ</a> or the <a rel="external nofollow" href="https://wordpress.org/support/plugin/google-sitemap-generator">support forum</a>.
            		</p></div>