BuddyPress.org

To get members of a specific group, use groups_get_group_members.
Found in buddypress\bp-groups\bp-groups-functions.php
Review the function to get all the parameters.
Example:

$args = array( 'group_id' => 99 ); 
$group_members = groups_get_group_members( $args );
var_dump( $group_members );

That solution was for the old templates – 6 years ago!

You could use this hook: do_action( 'bp_activity_entry_content' );
Found in: buddypress\bp-templates\bp-nouveau\includes\activity\template-tags.php
Again – no need to use a shortcode.

Did you assign the components to those pages?

Configure BuddyPress

That is not how shortcodes work.
You need to put it in the template:
buddypress\bp-templates\bp-nouveau\buddypress\activity\entry.php
Overload that template in your child theme and then make your change.
Since you are in the template, just make a call to a custom function – no need for a shortcode.

I’ve been testing this and found out that the code as is done in my previous post will break the members search feature from 3rd party plugins. So I modified this to use the “exclude” argument instead of the “include”.

Since doing this is going to be a heavy call on the server, I’ve decided to store my exclusion list in the DB as an option. I’m sure this could be done with transients so feel free to improve changing the storage of the array in a transient.

Note: shanebp mentioned this does not apply to ajax calls but it’s a filter to the members query so won’t it run whenever a call to the members is done no matter if it’s ajax or not if we exclude that piece of code?

Revised code follows. I tested this and it works fine for me.

/**
 * Only list active MemberPress members in the members directory.
 * sources:
 * https://buddydev.com/hiding-users-on-buddypress-based-site
 * https://buddypress.org/support/topic/member-loop-only-memberpress-members/
 * @param array $args args.
 *
 * @return array
 */
function tmp_only_show_members_in_directory( $args ) {
    // do not exclude in admin.
    if ( is_admin() && ! defined( 'DOING_AJAX' ) ) {
        return $args;
    }
    $args['exclude'] = tmp_get_users_to_exclude_from_directory();

    return $args;
}
add_filter( 'bp_after_has_members_parse_args', 'tmp_only_show_members_in_directory' );

/**
 * Returns an array of IDs to exclude, runs the queries if empty
 * @return false|mixed|void
 */
function tmp_get_users_to_exclude_from_directory() {
    $ids_to_exclude = get_option('tmp_update_members_to_exclude_from_directory');
    if (empty($ids_to_exclude) || !is_array($ids_to_exclude) || count($ids_to_exclude) < 1) {
        tmp_update_members_to_exclude_from_directory();
    }
    return get_option('tmp_update_members_to_exclude_from_directory');
}

// Scheduled Action Hook
function tmp_update_members_to_exclude_from_directory() {
    global $wpdb;
    $member_ids = $wpdb->get_col("SELECT DISTINCT user_id FROM ".$wpdb->prefix."mepr_transactions WHERE status IN('confirmed','complete') AND (expires_at >= NOW() OR expires_at = '0000-00-00 00:00:00')");
    $user_ids = get_users(['fields'=>'ID']);
    $user_ids_to_exclude = array_diff($user_ids, $member_ids);
    return update_option('tmp_update_members_to_exclude_from_directory',$user_ids_to_exclude);
}
add_action( 'hook_name', 'tmp_update_members_to_exclude_from_directory' );

// Schedule Cron Job Event
function tmp_update_members_to_exclude_from_directory_job() {
    if ( ! wp_next_scheduled( 'tmp_update_members_to_exclude_from_directory' ) ) {
        wp_schedule_event( current_time( 'timestamp' ), 'twicedaily', 'tmp_update_members_to_exclude_from_directory' );
    }
}
add_action( 'wp', 'tmp_update_members_to_exclude_from_directory_job' );

Please note the above solution won’t work if you have a custom table prefix (i.e. different than “wp_”).
I’ve put together this function using the bp_after_has_members_parse_args filter. Posting it here in case anyone needs it. So far it looks like it works fine.

/**
 * Only list active MemberPress members in the members directory.
 * sources:
 * https://buddydev.com/hiding-users-on-buddypress-based-site
 * https://buddypress.org/support/topic/member-loop-only-memberpress-members/
 * @param array $args args.
 *
 * @return array
 */
function tmp_only_show_members_in_directory( $args ) {
    // do not exclude in admin.
    if ( is_admin() && ! defined( 'DOING_AJAX' ) ) {
        return $args;
    }
    global $wpdb;
    $member_ids = $wpdb->get_col("SELECT DISTINCT user_id FROM ".$wpdb->prefix."mepr_transactions WHERE status IN('confirmed','complete') AND (expires_at >= NOW() OR expires_at = '0000-00-00 00:00:00')");
    $args['include'] = $member_ids;

    return $args;
}
add_filter( 'bp_after_has_members_parse_args', 'tmp_only_show_members_in_directory' );

This is already available.
Also check this link : https://wordpress.org/plugins/vibe-buddypress-woocommerce/