We use JIRA 6.2.
Seemingly randomly - an issue was transitioned between two statuses - Closed to Triage.
Where normally you see "username made changes", this change displays "made changes" only, with no identification.
The change happened on a issue that had apparently not been touched for a couple years. We can't see any triggering event to cause this issue transition and we haven't seen any transitions made by a blank user before.
See the below image for what the history entry looks like.Selection_002.png
What log levels do we need on to capture data about changes like this in the future and to troubleshoot this sort of "ghost transition" ?