Ordering by date not working [bug]

Support
1 
{% set options = { items: '@root.descendants', 'order': {'by': 'date', 'dir': 'asc'}, 'pagination': false } %}
{% set main_collection = page.collection(options) %}

{% for p in main_collection %}
	{% set image = p.media[p.header.image].cropZoom(540, 310) %}

	<article class="main-news">
	    <a href="{{ p.url }}" class="d-block mb-3">
	        <img src="{{ image.url }}" alt="{{ p.title }}" class="img-responsive w-100 rounded">
	    </a>

	    <a href="{{ p.url }}">
	        <h4>{{ p.title }}</h4>
	    </a>
	</article>
{% endfor %}

Item 1 has date: 03/04/2018 10:00
Item 2 has date: 03/04/2018 11:00

Item 2 is shown first, that’s right, but if i change date in Item 1 to 12:00, it won’t be first. Is it bug?