Attachment Manager bug after upgrade to JIRA 6

Question

We recently upgraded to JIRA 6. Users can no longer delete attachments that they added prior to the upgrade. Here's the behavior:

* User opens the "Manage Attachments" pane to display list of attachments,
* Under the "Attached By" column:* old attachments (i.e., added before the upgrade) list the UserName
* recent attachments list the User's "Full Name"

* Hover the mouse over the UserName (on the old attachments) and a popup label says "User does not exist". 
* The Delete icon (trash can) appears only on the recent attachments (thus preventing older attachments from being deleted.
* [Administrator can delete any/all attachments]

Update: Created support issue

Kevin Mote · Answer

No. We made no directory changes. We have always used LDAP for authentication against Active Directory.

Luther Hargrove · Answer

Did you recently change from using JIRA internal user directory to Crowd/Active Directory?