Xamarin forms shiny won't run when app is closed or screen is locked

I'm trying to do a scheduled task in xamarin forms using shiny but I can't make it work. I'm not sure what I'm doing wrong. It seems to work when I run the app in visual studio but when I unplugged it, it only runs once when I open the app. Any suggestions?

MainApplication.cs

 [Application]
    class MainApplication : Application
    {
        public MainApplication(IntPtr handle, JniHandleOwnership ownerShip) : base(handle, ownerShip)
        {
        }
        public override void OnCreate()
        {
            base.OnCreate();
            Shiny.AndroidShinyHost.Init(this, new ShinyTest.Startup());
        }
    }

Job Class

public class FirstJob : IJob
    {
        public FirstJob()
        {
        }

        public async Task<bool> Run(JobInfo jobInfo, CancellationToken cancelToken)
        {
            //things I want to do every job
            return true; // this is for iOS - try not to lie about this - return true when you actually do receive new data from the remote method
        }
    }

App.xaml.cs

public App()
        {
            InitializeComponent();

            MainPage = new MainPage();
        }

        protected override async void OnStart()
        {
            TimeSpan span = new TimeSpan(0, 0, 15, 0, 0);
            var job = new JobInfo(typeof(FirstJob), "FirstJob")
            {
                PeriodicTime = span,
                BatteryNotLow = false,
                DeviceCharging = false,
                RequiredInternetAccess = InternetAccess.Any,
                Repeat = true //defaults to true, set to false to run once OR set it inside a job to cancel further execution
            };

            // lastly, schedule it to go - don't worry about scheduling something more than once, we just update if your job name matches an existing one
            await ShinyHost.Resolve<Shiny.Jobs.IJobManager>().Schedule(job);
        }

Startup.cs

public class Startup : ShinyStartup
    {
        public override void ConfigureServices(IServiceCollection services)
        {
            
        }
    }

MainActivity

[Activity(Label = "ShinyTest", Icon = "@mipmap/icon", Theme = "@style/MainTheme", MainLauncher = true, ConfigurationChanges = ConfigChanges.ScreenSize | ConfigChanges.Orientation | ConfigChanges.UiMode | ConfigChanges.ScreenLayout | ConfigChanges.SmallestScreenSize )]
    public class MainActivity : global::Xamarin.Forms.Platform.Android.FormsAppCompatActivity
    {
        protected override void OnCreate(Bundle savedInstanceState)
        {
            TabLayoutResource = Resource.Layout.Tabbar;
            ToolbarResource = Resource.Layout.Toolbar;

            base.OnCreate(savedInstanceState);

            Xamarin.Essentials.Platform.Init(this, savedInstanceState);
            global::Xamarin.Forms.Forms.Init(this, savedInstanceState);
            LoadApplication(new App());
        }
        public override void OnRequestPermissionsResult(int requestCode, string[] permissions, [GeneratedEnum] Android.Content.PM.Permission[] grantResults)
        {
            Xamarin.Essentials.Platform.OnRequestPermissionsResult(requestCode, permissions, grantResults);
            Shiny.AndroidShinyHost.OnRequestPermissionsResult(requestCode, permissions, grantResults);

            base.OnRequestPermissionsResult(requestCode, permissions, grantResults);
        }
    }