iMessage no longer keeping chat archive?

Hello all!

So for long as I can remember iMessage on Mac always had a option to keep your messages in an archive, even if you deleted the actual conversation thread itself. I could delete a message and when I started it back up or that person messaged me it would bring back the entire conversation previous.

Now when I delete a message, it's gone. When I go to my archive folder in the library which would normally house my messages, its completely empty. Like not even my current messages that are still open are there. so iMessage is not archiving anything. What am I missing?