alguns ícones do Font Awesome carregam, outros não

Olá!

criei um menu com pseudo-elementos para colocar ícones do Font Awesome. Acontece que alguns ícones renderizam, outros aparecem somente como um quadradinho. O que pode ser?

CSS:

.phoen_nav_tab li {     border-bottom: 1px solid #dddd;     width: 100%;     margin-bottom: 7px;     padding-bottom: 7px; }  .phoen_nav_tab :first-child::before {     font-family: "Font Awesome 5 Free";      font-size: 12px;     content: "\f2d2"; }  .phoen_nav_tab :nth-child(2)::before {     font-family: "Font Awesome 5 Free" !important;      font-size: 12px;     content: "\f03a"; }  .phoen_nav_tab :nth-child(3)::before {     font-family: "Font Awesome 5 Free" !important;      font-size: 12px;     content: "\f17o"; }  .phoen_nav_tab :nth-child(4)::before {     font-family: "Font Awesome 5 Free" !important;      font-size: 12px;     content: "\f015"; }  .phoen_nav_tab :last-child::before {     font-family: "Font Awesome 5 Free" !important;      font-size: 12px;     content: "\f084"; } 

HTML:

<nav class="woocommerce-MyAccount-navigation phoen_custom_account">   <ul class="phoen_nav_tab">     <li class="woocommerce-MyAccount-navigation-link woocommerce-MyAccount-navigation-link-- is-active">        <a href="https://ouipetite.com.br/minha-conta//">Dashboard</a>     </li>     <li class="woocommerce-MyAccount-navigation-link woocommerce-MyAccount-navigation-link--orders">       <a href="https://ouipetite.com.br/minha-conta/orders/">My Orders</a>     </li>     <li class="woocommerce-MyAccount-navigation-link woocommerce-MyAccount-navigation-link--edit-account">        <a href="https://ouipetite.com.br/minha-conta/edit-account/">Edit Account</a>     </li>     <li class="woocommerce-MyAccount-navigation-link woocommerce-MyAccount-navigation-link--edit-address">       <a href="https://ouipetite.com.br/minha-conta/edit-address/">Edit Address</a>     </li>     <li class="woocommerce-MyAccount-navigation-link woocommerce-MyAccount-navigation-link--customer-logout">       <a href="https://ouipetite.com.br/minha-conta/customer-logout/?_wpnonce=3bacf0f819">Logout</a>     </li>   </ul> </nav>