Unfortunately, it's not a bug. This is how the new ABs work. Aside from 1-2 cases, all tiers have an either-or reward system. I can try to find the Peridia specific post if necessary, but they introduced it when Duel of Fates was released. Example, the last tier lists Droid Brains, Gyrda Keypads and Omis, but you only get either Droid Brains, or Gyrda Keypads, or Omis. Some tiers divide the rewards into groups and then use the either-or system. Like the tier you mentioned. Unless I'm mistaken, the Wirings, Transistors, Circuit Boards and Heatsinks are put in 1 group, then you receive only 1 of those mats. Simply put, it's all about RNG.
