症状
Script attached to 'SpawningBase_SpawnableObjectPrefab' in scene '' is missing or no valid script is attached.
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)
Script attached to 'AuthObjPrefab' in scene '' is missing or no valid script is attached.
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)
Script attached to 'GetCurrentRTTCallDoesntCrashWhenUseWebSockets_PlayerPrefab' in scene '' is missing or no valid script is attached.
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)
Script attached to 'SpawningBase_PlayerPrefab' in scene '' is missing or no valid script is attached.
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)
Script attached to 'PlayerWithAuthPrefab' in scene '' is missing or no valid script is attached.
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)
Script attached to 'NoAuthObjPrefab' in scene '' is missing or no valid script is attached.
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)
Script attached to 'PlayerCallbacksOrderOnTheHost_PlayerPrefab' in scene '' is missing or no valid script is attached.
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)
解決方法
PackageManagerから「Multi Player HLAPI」をバージョンアップする。