I see two possible issues.
The first has to do with the taxonomy field. Is it set to save and load terms? If this is not the case then post terms are not set and you will need to instead use a meta query.
The second issue has to do with
include( locate_template( 'includes/loop.php', false, false ) );
When using include() the global $post will not be defined in the included file. To have this global variable automatically defined in that template then you need to use get_template_part() or you need to manually define the variable in the file with global $post;
