Hi!
Thanks for your reply. I do think you are mistaken, because it actually does work. I’ve done it now multiple times. With a button i can schedule a notification in the future for myself (current logged in user) with the PWA app.
But i fixed the problem now, instead of using math in the scheduled notification, i’ve created a way to get the date/time i want to send the reminder, as a property in the database and then it is a simple magic text with no formatting.
So i’ve fixed the issue myself 
, but a reminder, you can actually schedule notifications for yourself.