Yes, it all happens on one device. I use the application on only one device. After installing the application, I set all the settings in it manually.
I just found out that notifications of this task can work normal, but it depends on the due date. What connection is I don’t understand. I set the due date for today at 5:00 pm and the first notification arrived in time. Then at the same moment I changed the due date for today at 5:05 pm and the first notification came at 5:15 pm.
Attached screenshots.