Query for topic set as is_home

[MZAWeb]

When you query a single topic, the resulting WP_Query has is_home as true and is_singular as false.

To replicate:

var_dump( new WP_Query( 'topic=test' ) );

Replace 'test' with the post_name of one of your topics

[MZAWeb]

WP's parse_query doesn't seem to handle custom post types query_vars to set is_single.

This feels more like a hack than a solution, but it works:

add_filter( 'parse_query', 'fix_topic_query' );

function fix_topic_query( $query ) {
    if ( empty( $query->query_vars['topic'] ) )
        return;

    $query->is_singular = true;
    $query->is_single   = true;
    $query->is_home     = false;
 
}

[MZAWeb]

Sorry, ignore. Need to debug this a bit more before reporting.