Are you using a checkbox field or a true/false field.
Checkboxes are stored as serialized data and you’re not going to be able to use WP_Query to filter by a checkbox field.
If you use a true/false field then you can use WP_Query, the values of a true/false field are 0 (zero) for false and 1 for true.
the last code example you have should work for a true/false field if use substitute 0 & 1 where you have true and false.
