I was playing as Gor-Rok on Mortal Empires, and I searched a ruin which gave me this image.
The main issue I have with this is that no dice makers worth their salt would create a set of dice and carve the symbols differently between the same dice of a set. The issue I have belongs with the middle dice in that the curved T symbol needs to be rotated 90 degrees to the left in order to match up with the top and right dice, otherwise the riddle points towards the A-like symbol being the missing icon unless you only examine the top dice.
I know this is a rather minor suggestion but it does provide two answers to what the ? would be depending on which dice you look at first.
Thank you for your time.