Hi.
I was recently trying to obtain the blessing material 'Essence of Gold', one of the choices in the 'Drops' selection links to the stage "Rescue of Princess Ethel", the Essence of Gold material is not obtainable through raiding this stage..
I would guess if it is on this stage It is in a box or treasure chest and otherwise not accessible through raiding.
I just wasted abunch of stamina and sweep tickets for nothing. This should be fixed.