agent did not receive email invite to submit candidate to a requisition

Content

Recruiter invites agent to submit candidate for the requisition. I am expecting the agent to receive an email "Request to Submit Candidate", but no email received. 

On the other hand, the agent did receive a bell alert notification when logged in at the agency portal.  

The IRC_Agent_Invite_Alert is enabled in the alerts composer. I did not make any changes. Just default settings