WordPress Meta Query: Relation is not working correctly

What you posted suggests that there are no posts that match, in which case 0 results is correct.

I don’t think that the meta_query is broken. The SQL looks right to me, which means that you don’t have the meta_key/meta_value pairs in the database that you think you do, or that something else about the query is wrong– post_type, post_status, the cat condition, something.

error code: 523