When browsing the commit list on Stash, however, I someties find that there's no profile picture of the user nor a link to that user's Jira or Confluence profile page.
The reason for this is that the user has a different email in his/her
~/.gitconfig than what's registered for that user in Atlassian
The fix is easy, just two steps:
Head over to your profile page on Confluence or Jira and check the email address there.
~/.gitconfigin your favourite editor and make sure the email reads the same as what you found on your Confluence profile page:
[user] name = John Doe email = firstname.lastname@example.org