Push Notifications to specific users does not work

OK. I’m stumped. I have push notifications setup and it works as expected when sending to all users. However, when I try to send it to a specific user, it won’t work under any circumstances.

Trying to isolate the problem, I have bypassed generating a column for the recipient and have hardcoded an email address into the send action in the email field (see photo).
Screenshot 2024-06-07 214457

Again, sending to all users works just fine, but choosing one of those users and hardcoding their email into the send action does not work. They do not receive the notification.

I don’t even know what could be wrong!?