Multiple post types in loop

Hi there,

I'm trying to create a loop on one of my pages that includes multiple post types. The code I currently have is:

{% set pt = { array( 'news', 'guide' ) } %}
{% set args = { post_type: pt, posts_per_page: 12, facetwp: true } %}

{% set posts = mb.get_posts( args ) %}

{% for post in posts %}
	<h1>
		{{ post.title }}
	</h1>
{% endfor %}

However, this throws an error. Could you please tell me what I'm doing wrong?

Thanks!