Sometimes the grouped attributes or values are text aligned right, because of WooCommerce styles.
Please add the following custom CSS to solve this problem:
.woocommerce table.shop_attributes th {
text-align: left;
}
.woocommerce table.shop_attributes td {
padding: 0;
}


Not only have my attributes turned white but they are appearing as normal and not grouped despite setting up groups and linking these together.