ACP2E-3523: Issue with Default Attribute Option Value Behavior for Multiselect

Author: aplapana

app/code/Magento/Catalog/view/adminhtml/templates/catalog/product/attribute/options.phtml

@@ -78,7 +78,7 @@ $stores = $block->getStoresSortedBySortOrder();
                 <input data-role="order" type="hidden" name="option[order][<%- data.id %>]"  value="<%- data.sort_order %>" <?php if ($block->getReadOnly() || $block->canManageOptionDefaultOnly()):?> disabled="disabled"<?php endif; ?>/>
             </td>
             <td class="col-default control-table-actions-cell">
-                <input class="input-radio" type="<%- data.intype %>" name="default[<%- data.id %>]" value="<%- data.id %>" <%- data.checked %><?php if ($block->getReadOnly()):?>disabled="disabled"<?php endif;?>/>
+                <input class="input-radio" type="<%- data.intype %>" name="default[<% if (data.intype === 'checkbox') { %><%- data.id %><% } %>]" value="<%- data.id %>" <%- data.checked %><?php if ($block->getReadOnly()):?>disabled="disabled"<?php endif;?>/>
             </td>
             <?php foreach ($stores as $_store):?>
             <td class="col-<%- data.id %>"><input name="option[value][<%- data.id %>][<?= (int) $_store->getId() ?>]" value="<%- data.store<?= /* @noEscape */ (int) $_store->getId() ?> %>" class="input-text<?php if ($_store->getId() == \Magento\Store\Model\Store::DEFAULT_STORE_ID):?> required-option required-unique<?php endif; ?>" type="text" <?php if ($block->getReadOnly() || $block->canManageOptionDefaultOnly()):?> disabled="disabled"<?php endif;?>/></td>