Some worklog display in user name instead of full name after JIRA upgraded from 5.1 to 6.0

We had JIRA upgraded from 5.1 to 6.0. The worklog detail was displayed with user full name, but after upgrade to 6.0, worklog of some users are displayed with user name instead of user full name while others are still displayed in user full name. And even for those users whose worklog before upgrade are displayed in user name, their new worklog after upgrade in 6.0 is displayed with user full name.

It causes the worklog record in Tempo plugin to be displayed separately with user name and user full name as two lines. and it bring difficulty to do statistics.

A sample as below:

• First worklog is displayed with user name
• Second worklog is displayed with user full name