What you were expecting to happen, and what actually happened?
Bought the Gladiators Pack, expected to get two Arcane Skull Traitstones, just got one instead.
What are the steps to make it happen again?
Check your Collection that you have zero Arcane Skull Traitstones, buy the Gladiators Pack, check back to see you’ve only got one Arcane Skull Traitstone afterwards.
At least it appears to be universal… the devs are aware of this and are looking into it. Hope to get an answer in the next 12 hours (or less!), I bought a few of those things myself.