How to search for a group where a meta field equals a specific string with bbPress?

I'm going nuts over this... I need to make bbPress group search to find only those groups where a specific string is inside a meta field.

I tried what I found here: https://codex.buddypress.org/plugindev/group-meta-queries-usage-example/

I use a different meta field, but tried to implement this as it should be. I can update and read the meta value, but I cannot make the meta_query thing work.

I can see the filter_ajax_querystring function is being executed, because I placed a couple of echo's there to test, and the search term is also there, it only doesn't find the group with the meta key - and it is there.

Anyone who can shed some light? What am I missing?

This is my groups-loop:

    $params['meta_query'] = array(
        array(
            'key'     => 'bp_symbol_code',
            'value'   => $_REQUEST['s'],
            'compare' => '='
        )
    );

    if ( bp_has_groups( bp_ajax_querystring( 'groups' ) . '&' . http_build_query( $params ) ) ) {
        while ( bp_groups() ) {
            bp_the_group();
            // redirect after header definitions - cannot use wp_redirect( $location );
            ?>
               <script type="text/javascript">
               <!--
                  window.location= '<?php echo bp_group_permalink(); ?>';
               //-->
               </script>
            <?php
        }
    }

Ok, I feel stupid....

This was the problem:

if ( bp_has_groups( bp_ajax_querystring( 'groups' ) . '&' . http_build_query( $params ) ) )

bp_has_groups() was receiving both an array and a query string...

So the solution was just to change the above with this:

if ( bp_has_groups( array_merge( bp_ajax_querystring( 'groups' ), $params ) ) )

Thanks Gavin, your comments eventually made me realise that mistake :)