According to our Adobe Technical Account Manager, it turns out this issue was supposedly fixed in 220.127.116.11 but it is still a present issue in 18.104.22.168. Perhaps the fix was removed or reverted in SP3 Cumulative Fix Pack 1? He also mentions it is fixed in internal builds of 6.5 but not yet released.
At this point we are likely going to request a backport fix for our current AEM version, via a Daycare ticket.
However, we are also in the process of testing an upgrade to 6.4.3. I'm wondering, do you know if this is fixed in that version?