Object workflow not triggering notification in bell icon

Summary:

I have configured a notification in email template and created object workflow, An Acknowledge email should be received to employee when helpdesk request is created.

Content (please ensure you mask any confidential information):

I have configured a notification in email template and created object workflow, An Acknowledge email should be received to employee when helpdesk request is created. I am only receiving the notification in email but not in bell icon. Please suggest

FYI, I also created using standard objects, HR Helpdesk > Server Scripts and set the notification preferences, This is trigerring both email and bell icon but i could not able to change the subject line of the email with this approach. Oracle recommended to user Object workflow and email template to have a custom subject but i am not receiving notifications with object workflow