All "Conversations" settings are off; So why is Sent email still grouped by "Conversation"?

I found it harder to locate specific email messages when "Conversations" settings are on, so I turned them all off. Though this works for InBoxes, my Sent messages are still being grouped. If this isn't entered into Apple's database as a bug, it should be.

I really and truly do not want "Converstions" in any mailbox, including Sent email.

Thank you.