.find() not working with live preview?
As noted in the comments above, eager-loading is not yet compatible with Live Preview. A clean workaround is to disable eager-loading in the template when the page is being viewed in Live Preview:

{% if craft.request.isLivePreview %}
    {% set images = entry.gallery %}
{% else %}
    {% set images = craft.assets({
        relatedTo: {sourceElement: entry.id, field: 'gallery'}
    }) %}
{% endif %}

{% for image in images %}
    {{ image.url }}&lt;br /&gt;
{% endfor %}