Question [Bug?] Custom EventUnit<T> disappear from dropdown list

Visual Scripting version: 1.7.8
Unity version: 2021.3.0f1

After coding and regen nodes, custom EventUnit disappear from dropdown list.
The already exist custom EventUnit work fine, e.g. Effect_OnDestroy node.
I create a new project, use the same code, it's work fine.

Code (CSharp):

1. using Unity.VisualScripting;
2.  
3. namespace Gameplay.Ability.VisualScripting
4. {
5.     [UnitCategory("Events\\Gameplay")]
6.     public abstract class EffectGamepleyEvent : EventUnit<GameplayEventArgs>
7.     {
8.         [DoNotSerialize]
9.         public ValueOutput Sender { get; private set; }
10.         [DoNotSerialize]
11.         public ValueOutput EventArgs { get; private set; }
12.  
13.         protected override bool register => true;
14.  
15.         protected override void Definition()
16.         {
17.             base.Definition();
18.             Sender = ValueOutput<EffectObj>(nameof(Sender));
19.             EventArgs = ValueOutput<GameplayEventArgs>(nameof(EventArgs));
20.         }
21.  
22.         protected override void AssignArguments(Flow flow, GameplayEventArgs data)
23.         {
24.             flow.SetValue(Sender, flow.stack.component.gameObject.GetComponent<EffectVisualScripting>().Sender);
25.             flow.SetValue(EventArgs, data);
26.         }
27.     }
28.  
29.     [UnitTitle("Effect_OnCreated")]
30.     public sealed class Effect_OnCreated : EffectGamepleyEvent
31.     {
32.         public override EventHook GetHook(GraphReference reference)
33.         {
34.             return new EventHook(nameof(Effect_OnCreated), reference.gameObject);
35.         }
36.     }
37.  
38.     [UnitTitle("Effect_OnDestroy")]
39.     public sealed class Effect_OnDestroy : EffectGamepleyEvent
40.     {
41.         public override EventHook GetHook(GraphReference reference)
42.         {
43.             return new EventHook(nameof(Effect_OnDestroy), reference.gameObject);
44.         }
45.     }
46.  
47.     [UnitTitle("Effect_OnPeriod")]
48.     public sealed class Effect_OnPeriod : EffectGamepleyEvent
49.     {
50.         public override EventHook GetHook(GraphReference reference)
51.         {
52.             return new EventHook(nameof(Effect_OnPeriod), reference.gameObject);
53.         }
54.     }
55. }
56.  

# Other Error:

Objects are trying to be loaded during a domain backup. This is not allowed as it will lead to undefined behaviour!