Bug, not a feature. Shadowkin FW is bugged and this has been passed along to the devs.
speaking of FW bugs, I noticed another issue recently.
Even when you beat a stage for the first time, the energy requirements for the next stage are set to that of a super raid. I beat stage 6 with 3 keys left and then clicked next, it said I don't have enough keys. Had to go out to the stage selection screen and then back in directly to stage 7.