same thing has happened to me also. I ran kell's fall many times with no drops, frustrated I checked my collections and it was missing completely, just not there. this is a bug not many players has to deal with but it is frustrating because i paid for this content. to be clear, I never finished act 3 of previous season which starts the mission. I just quit playing D2 for a while then came back to edge of fate. after running kell's fall many times with no drop, I was reading raddit and someone posted they had to collected from their collection after they were having trouble. I decided to check my collection and Slayer Fang is just not part of the collection. I can UL screenshots of my collection tab for proof also, maybe same you some future trouble, Barrow Dyad also not showing in collection. i paid for that season, it should at least show up in collection grayed out.