Riot Please Fix Death Damage Sheets / Damage Sheet Bug

A couple of times now, after dying I've checked the damage calculation and there's a grey box without icon and the player's name who dealt some minor damage.

This time it bugged me because I was running away and had 35hp or so and died to Brand's passive, I checked the damage and Miss Fortune did 40 damage, but it didn't tell the source only the MF account name, so I was annoyed because I might've survived if that damage wasn't dealt, obviously I died yes but I'm expecting the system to clearly tell me what did and what.

Now that I don't know what the damage was, early game engages might turn accidentally lethal as 40 unknown damage is quite a big of a deal. Is it a rune? An item? Bug? What?