Creating new AppDomain instances inside a Windows service doesn't work

Question

I am trying to create a Windows service with C# which spawns multiple processes inside it.
For this I am using AppDomain functionality and creating multiple of them at startup in the OnStart method of my service:

    public partial class MyService : ServiceBase
    {
        public ServiceBase()
        {
            InitializeComponents();
        }
    
        protected override void OnStart(string[] args)
        {
            var setup = new AppDomainSetup();
            setup.ApplicationBase = Path.GetDirectoryName(GetMyExePath());
            var ad = AppDomain.CreateDomain("Domain NEW", null, setup);
            var t = new Thread(() => {
                    ad.ExecuteAssembly(GetMyExePath());
                    AppDomain.Unload(ad);
                });
            t.Start();
        }
    }

(I know I should put a check to prevent recursively starting new domains from each new one, but for now it doesn't even start the first one)

When I try the same in a Console Application, it works fine. But when I build it as a Windows Service and run it from the service manager, it seems to terminate after startup.

Opening the Event Viewer, I see this about my service:

"Service can not be started. An instance of the service is already running."

Running it without the app domain creation code works just fine. It fails to start even a single domain as it seems to view them as trying to start the same process twice instead making a new domain within the process.

Is there a way to get this to run on services or does it only work for regular applications?