Mentioning users behaves differently between Jira and JSM

Issue Summary

Mentioning customers (Request Participants) behaves differently if we add the comment through Jira's view issue screen or JSM's request page.

If we mention the user on Jira's screen, the "Mentioned" notification is not sent.
If we mention the user on JSM's screen, the "Mentioned" notification is sent.

Note: Mentioned notification refers to Jira's URLs so customer may be directed to a screen stating issue does not exist if the customer has Jira access but no access to that specific project.

Steps to Reproduce

1. Add customer as Request Participant
2. Mention user (@username) on a comment through both screens

Expected Results

User should either receive the notification both times or not receive any of them.

Actual Results

User receives notification only if sent from JSM screen

Workaround

Currently there is no known workaround for this behavior. A workaround will be added here when available