Unable to stop watching a case when started watching it through a comment on transition screen.

Issue Summary

When as an administrator or Jira SD Agent you start watching an Issue via an Issue comment within a transition screen, you are unable to watch the Issue by clicking on Stop watching this issue once.

This is reproducible on Data Center: yes

Steps to Reproduce

1. Create a Project of type Service (ITSM) using sample data
2. Log into the Portal with a non-agent user and create an Issue
3. Log into the Jira UI with an SD agent and transition the previous Issue. Make sure the transition has a screen configured where you can add a comment so that you can auto-watch the Issue.
4. Try to stop watching the case
5. * Refresh the page

Expected Results

1. Jira users should stop watching the case by clicking on Stop watching this issue once.

Actual Results

1. Clicking on Stop watching this issue will change the link text to Start watching this issue, but the numbers of watchers does not decrease:
2. If you refresh the page, you can see the text Stop watching this issue again:

Workaround

Workaround 1 (Preferred)

1. Click on Stop watching this issue once, then click on Start watching this issue again.
2. Finally, click on Stop watching this issue to completely stop watching the Issue.

Workaround 2

1. Click on More > Watch Issue, and repeat once more.
2. This will enable Stop watching, click on it to completely stop watching the Issue.