I cannot get checkboxes to save properly

Either it assigned fields.tags as true or doesn't change, or doesn't save. similar attempts will change the variable on the page, but not save in the database.

vue section

<div class="form-group">
    <div class="control-label" :class="Defines.cssform.label">Tags:<br><small class="text-muted">(select all that apply)</small></div>
    <div v-for="item in category('CONTACT_memo_subcategories')" :key="item" >
          <input type="checkbox"  :value="item.id"  v-model="fields.tags"><label></label>
    </div>
</div>

php api section

public static function getClientMemo ($api, $args) {
    $data   = $api->getArgs();
    $client_id=$args;
    $staff_id=$api->authentication->getUser()->id;
    if (is_array($staff_id)) $staff_id=$staff_id['id'];
    $programs = '('.implode(',',ProgramStaff::getPivots('id_staff', $staff_id)).')';
    $programs = ($programs=='()') ? '' : ' (ids_program IN '.$programs.') OR ';
    $entries = self::getEntries(['as_array' => true, 'limit' => null, 'only_entries' => true, 'where' => [" ( id_client = ".$client_id." AND deleted = 0 AND ( ( (ids_program is null OR ids_program='') AND (ids_staff is null OR ids_staff='' OR ids_staff='[]' OR ids_staff='()')) OR ".$programs." json_contains(json_array(ids_staff),'".$staff_id."') ) ) "]] );

    foreach ($entries as $entry) {
        $entry['tags'] = is_null($entry['tags']) ? [] : json_decode($memo['tags']);
    };
    error_log(var_export($entries,true));
    return $entries;
}

public static function updateClientMemo ($api, $args) {
    $memo       = $api->getArgs();
    $memo['client_id']  = $args[1];
    $memo['tags'] = is_null($memo['tags']) ? [] : json_encode($memo['tags']);
    $memo['deleted']        = 0;
    $memo['date']           = date_create_from_format('m/d/Y', $memo['date']);
    $memo['reminder_date']  = date_create_from_format('m/d/Y h:i a',$memo['reminder_date']);
    $memo['modified_at']    = date('Y-m-d H:i:s');
    $memo['modified_by']    = $api->authentication->getUser()->id;
    error_log(var_export($memo,true));
    $entry = self::getEntry(['where' => ['id = ?', $memo['id']]]);
    $entry->setData($memo);

    return $entry->save();
}