notification_fail.cs

var toast = ToastContentFactory.CreateToastText02();
var item = x.First();

toast.TextHeading.Text = item.Subject.Type;
toast.TextBodyWrap.Text = "DO IT";
toast.Lang = "en_US";
toast.BaseUri = "http://google.com";
toast.Duration = BoxKite.Notifications.ToastDuration.Long;
toast.StrictValidation = false;

ToastNotificationManager.CreateToastNotifier().Show(new ToastNotification(toast.GetXml()));

TO THE MANIFEST

This works for me:

var toast = ToastContentFactory.CreateToastText02();

toast.TextHeading.Text = "A Thing!";
toast.TextBodyWrap.Text = "DO IT";
toast.Lang = "en-US";
toast.BaseUri = "http://google.com";
toast.Duration = BoxKite.Notifications.ToastDuration.Long;
toast.StrictValidation = false;

ToastNotificationManager.CreateToastNotifier().Show(new ToastNotification(toast.GetXml()));

Lang was en_US when it needs to be en-US. I think that's all that was missing.

Apparently assigning .Lang makes it not appear.

You can use the Event Log to check for errors when your toast notification does not display. Look for events involving your toast notification in the Event Viewer under Applications and Services Logs > Microsoft > Windows > Immersive-Shell > Microsoft-Windows-TWinUI > Operational.

Anything there that might help?