Comments of user who have umlaut in their names can't be seen.

As I commented an issue I wondered why I don't see the comment. I commented again and I still didn't see it. As I tried the third time and didn't see the comment I recognized the beginning of my first comment: Comment by
As I don't see my correct full name on right top: User: J?rg Meier instead of User: Jörg Meier I changed my name to Joerg Meier and now both works.
Whats the difference between your jira.atlassian.com which shows my full name including umlaut correct and mine??