My friend and I made a hardcore world this Monday and have been playing 6-8 hours daily, but have not had a single raid yet. We killed the first two bosses already. Maybe it's a bug with the pts? Maybe we're just incredibly lucky? I can't believe I'm asking for troll raids, but the leather would have been nice for armor.
We had this happen before. Turns out someone triggered a raid at a rarely used base and left. We didn’t have raids again until we visited that base and let the timer finish on it.