问题未出现，未显示或隐藏在加载程序div中

<div class="gallery-placeholder _block-content-loading" data-gallery-role="gallery-placeholder">
    <div data-role="loader" class="loading-mask">
        <div class="loader">
            <img src="<?php /* @escapeNotVerified */ echo $block->getViewFileUrl('images/loader-1.gif'); ?>"
                 alt="<?php /* @escapeNotVerified */ echo __('Loading...') ?>">
        </div>
    </div>
</div>
<!--Fix for jumping content. Loader must be the same size as gallery.-->
<script>
    var config = {
            "width": <?php /* @escapeNotVerified */ echo $width; ?>,
            "thumbheight": <?php /* @escapeNotVerified */ echo $thumbHeight ?: $thumbWidth; ?>,
            "navtype": "<?php /* @escapeNotVerified */  echo $block->getVar("gallery/navtype"); ?>",
            "height": <?php /* @escapeNotVerified */ echo $height; ?>
        },
        thumbBarHeight = 0,
        loader = document.querySelectorAll('[data-gallery-role="gallery-placeholder"] [data-role="loader"]')[0];

    if (config.navtype === 'horizontal') {
        thumbBarHeight = config.thumbheight;
    }

    loader.style.paddingBottom = ( config.height / config.width * 100) + "%";
</script>