It occure only when we add the item. If we save the menu it works
I found the problem, if your innerblocks is in a template locked you need to add templateLock="false"
like that echo '<InnerBlocks allowedBlocks="' . esc_attr( wp_json_encode( $allowed_blocks ) ) . '" templateLock="false" />';
Hello, same probleme the options page field return NULL in the secondary language. I think Jonathan is right this is the lastest versions.