ForceSyncVirtualPlayer.cs

// https://discussions.unity.com/t/multiplayer-playmode-does-not-update-assembly-properly/922976

using System;
using System.Reflection;
using UnityEditor;
using UnityEngine;

internal class ForceSyncVirtualPlayer : AssetPostprocessor
{
    private const string SessionStateKey = "ForceSyncVirtualPlayer.CachedTotalCount";

    private static void OnPostprocessAllAssets(string[] importedAssets, string[] deletedAssets, string[] movedAssets, string[] movedFromAssetPaths, bool didDomainReload)
    {
        var totalCount = importedAssets.Length + deletedAssets.Length + movedAssets.Length + movedFromAssetPaths.Length;

        if (!didDomainReload)
        {
            SessionState.SetInt(SessionStateKey, totalCount);
            return;
        }

        var cachedTotalCount = SessionState.GetInt(SessionStateKey, 0);
        if (cachedTotalCount == 0) return;

        _targetType ??= Type.GetType("Unity.Multiplayer.Playmode.VirtualProjects.Editor.AssetDatabaseCallbacks, Unity.Multiplayer.Playmode.VirtualProjects.Editor");
        if (_targetType == null)
        {
            Debug.LogError("Target type not found.");
            return;
        }

        _eventField ??= _targetType.GetField("OnPostprocessAllAssetsCallback", BindingFlags.Static | BindingFlags.NonPublic);
        if (_eventField == null)
        {
            Debug.LogError("Event field not found.");
            return;
        }

        _eventDelegate = (Delegate) _eventField.GetValue(null);
        if (_eventDelegate == null)
        {
            Debug.LogError("Event delegate not found.");
            return;
        }

        _eventDelegate.DynamicInvoke(true, cachedTotalCount);
        SessionState.EraseInt(SessionStateKey);
    }

    private static Type _targetType;
    private static FieldInfo _eventField;
    private static Delegate _eventDelegate;
}