WP Query with multiple taxonomies returns 0 results

The aim is to return 3 posts from 2 separate taxonomies.

My query:

$weeks = new WP_Query([

    //Weeks post type
    'post_type' => 'sfwd-lessons',
    'tax_query' => [
        'relation' => 'AND',

        //Intensity Level Category
        [
            'taxonomy' => 'ld_lesson_category',
            'field' => 'slug',
            'terms' => ['low-seated']
        ],

        //Week nos tags
        [
            'taxonomy' => 'ld_lesson_tag',
            'field' => 'slug',
            'terms' => ['week1', 'week2', 'week2-test'],
            'operator' => 'IN'
        ]
    ]

]);

If I remove the tax query, all posts are returned. With the tax_query, no posts. It should return 3 posts.