Здравствуйте, Pablo Cabaneiro, Вы писали:
упрощенный рабочий пример

// app 1
    class Program
    {
        static void Main(string[] args)
        {
            EventWaitHandle waitHandle = new EventWaitHandle(false, EventResetMode.ManualReset, "EventWaitHandle");
            Console.ReadKey(false);
            waitHandle.Set();
        }
    }

// app 2
    class Program
    {
        static void Main(string[] args)
        {
            try
            {
                EventWaitHandle waitHandle = EventWaitHandle.OpenExisting("EventWaitHandle");
                Console.WriteLine("Waiting");
                waitHandle.WaitOne();
                Console.WriteLine("Wait completed");
                
            }
            catch(WaitHandleCannotBeOpenedException e)
            {
                Console.WriteLine("EventWaitHandle not found");
                Console.WriteLine(e.Message);
            }
            Console.ReadKey(false);
        }
    }