Notification not sent when adding mention to comment when editing

Scenario 1: OK
Add a comment to a line in a file while viewing the diff of a pull request.
Add a mention of a Stash user and some text.
Save the comment.
Result: the mentioned user gets a notification email (working as expected).

Scenario 2: NOK
Now add a comment and do the same except adding the mention.
Save the comment.
Go to the pull request overview tab.
Edit the comment and add the mention.
Save the comment.

Expected result: the mentioned user should get a notification email.
Actual result: the mentioned user does NOT get an email.