Weird WP_Query issue – meta_query not being added to query_vars

Hi everyone, it’s my first time posting here, let me know if I am doing something wrong ??

I have a very puzzling issue with WP_Query. I am pretty sure it’s not a bug, but I am running out of ideas. I’ve been using WP_Query with meta_query for ages now and on one theme I’m working on it’s producing weirdness, here’s what’s up, through an example:

$args = array(
	'post_type' => 'property',
	'meta_query' => array(
		array(
			'key' => 'mykey',
			'value' => 'myvalue',
			'compare' => '='
		)
	)
);

$stupid = new WP_Query( $args );

The issue is that the meta_query is not used at all. If you print out $stupid it should be added to query_vars but it is shown as an empty array:

[query_vars] => Array
        (
            [post_type] => property
            [meta_query] => Array
                (
                )

            [error] =>
            [m] => 0
            [p] => 0
            [post_parent] =>
            .... etc

I have tried doing this every which way, copy-pasting from the codex, using the set() method, using query_posts after the fact, nothing works.

As I mentioned, I’ve used this hundreds of times before, on 3.5.2 as weel, so I doubt it is a bug. It must be something theme-related, anyone have any ideas what it could be?

I have no custom ‘pre_get_posts’ stuff going on or anything else of that nature. I’ll wade through the source code for WP_Query but if anyone has any ideas in the meantime I would be super thankful!

Thank you ??

Daniel