It is a grace event, i rolled back to the chloe kiss scene and skipped through skipping miya sex and some other stuff and you get a pic from grace. I dunno what exactly is the trigger for the event check tho.
Sorry for the late reply but I found out . It's really a grace event but all I was missing was some Grace points which I didn't get from the evidence puzzle. I thought those didn't give you any cuz the game doesn't show you points gained at the instant which is a different system from other games like Eternum (I respect it tho!) Anyways , you gotta say some smart stuff during the puzzle to get the points.