Removed user from notifo can't be added back

I’ve removed a user from notifo that was automatically added previously but now, I can’t seem to make it work again.

I was expecting that user to be added back automatically. I’ve tried to logout and login again (on squidex and notifo).

I’ve also tried to add him again manually on notifo but, the notification icon on squidex doesn’t even appear (tried logout/login also).

What am I missing here? When should users be synced between the two apps?
Regards,
Thank you

I think the User is added back when any change happens to his profile.