MODELからレコードが取得できない

以下のcontroller からMODELのfunctionを呼び出していますが、DBから取得できるレコードがNULLになってしまいます。
composer auto-load を実行しても改善されません。
model側で$this を確認すると、レコードがからのモデルのオブジェクトの内容は確認できます。
もちろん、DBにはレコードが存在します。
どこが悪いのかご助言をお願いできますでしょうか。

laravel v6.5
Mysql v8.0.18

<controller> ``` namespace App\Http\Controllers;

use Illuminate\Http\Request;
use Illuminate\Http\Middleware\VerifyCsrfToken;
use Illuminate\Support\Facades\Validator;
use Illuminate\Support\Facades\Log;

use App\Model\RP;
use Carbon\Carbon;

class RPController extends Controller
{
function index(Request $request)
{
if(isset($request->display_items)){
$paginate = $request->display_items;
}
else {
$paginate = 20;
}
if(isset($request->page)){
$page = $request->page;
} else {
$page = 1;
}
$display_items = $paginate;

    $page_params = array();
    $page_params['size'] = 20;
    $page_params['direction'] = "ASC";
    $rp_info = \App\Library\Pz::getRP($page_params);

    $rp_clients = new RP();
    $rp_clients = $rp_clients->getRPClient($rp_info[0],'client_id');
 
    $total_count = count($rp_info[0]);
            
    $start_record = ($page - 1) * $paginate + 1;
    $end_record = ($page * $paginate >= count($rp_info) ) ? count($rp_info) : $page * $paginate;

    $pagination_params = [
        "display_items" => $display_items,
    ];
    
    return view('rp/index', compact('rp_clients', 'start_record', 'end_record', 'total_count',
                                          'display_items', 'pagination_params'));
}


<model>

namespace App\Model;

use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\SoftDeletes;

use Carbon\Carbon;

class RP extends Model
{
use SoftDeletes;

protected $table        = 'rp';
public    $tableType    = 'master';

protected $primaryKey   = 'id';
protected $keyType      = 'bigint';
public    $incrementing = true;

protected $dates = ['deleted_at'];
protected $fillable = ['client_id', 'service_name', 'description', 
                       'oidc_login_redirect_url', 'oidc_logout_redirect_url',
                       'oidc_client_secret', 'wifi_stadium_id', 'wifi_home_club_cd', 'enabled',
                       'display_pattern', 'display_header_footer', 'display_agreement_check', 
                       'login_button_pattern', 'register_timestamp', 'register_principal',
                       'update_timestamp', 'update_principal'];

// created_at, updated_at は DB の機能で自動更新する.
public $timestamps = false; 

public function getRPClient($parentAry, $target){
    foreach($parentAry as $childAry){
        foreach($childAry as $key => $value){
            if($key == $target){
                $targetAry[] = ['client_id'=>$value,'description'=>$this->description,'enabled'=>$this->enabled];
            }
        }
    }
    return $targetAry;
}

}


<migration1>

<?php use Illuminate\Database\Migrations\Migration; use Illuminate\Database\Schema\Blueprint; use Illuminate\Support\Facades\Schema; class CreateRpTableForRds extends Migration { /** * Run the migrations. * * @return void */ public function up() { Schema::create('rp', function (Blueprint $table) { $table->bigIncrements('id'); $table->string('client_id'); $table->string('service_name'); $table->string('description')->nullable(); $table->string('oidc_login_redirect_url'); $table->string('oidc_logout_redirect_url'); $table->string('oidc_client_secret')->nullable(); $table->string('wifi_stadium_id')->nullable(); $table->string('wifi_home_club_cd')->nullable(); $table->boolean('enabled')->nullable(); $table->string('display_pattern')->nullable()->comment('"00": ミニマム、"01":標準、"02":フル'); $table->boolean('display_header_footer')->nullable()->comment('画面のヘッダ・フッタを表示／非表示'); $table->boolean('display_agreement_check')->nullable()->comment('規約同意チェックボックスの表示／非表示'); $table->string('login_button_pattern')->nullable()->comment('"00":標準、"01":メールアドレス'); $table->bigInteger('register_timestamp')->nullable(); // Unix Timestamp $table->string('register_principal')->nullable(); $table->bigInteger('update_timestamp')->nullable(); // Unix Timestamp $table->string('update_principal')->nullable(); }); } /** * Reverse the migrations. * * @return void */ public function down() { Schema::dropIfExists('rp'); } } ``` <migration2> ``` <?php use Illuminate\Database\Migrations\Migration; use Illuminate\Database\Schema\Blueprint; use Illuminate\Support\Facades\Schema; class AddSoftDeleteRpTableForRds extends Migration { /** * Run the migrations. * * @return void */ public function up() { Schema::table('rp', function (Blueprint $table) { $table->softdeletes(); }); } /** * Reverse the migrations. * * @return void */ public function down() { Schema::table('rp', function (Blueprint $table) { $table->dropColumn('deleted_at'); }); } } ```