I completed the achieve to earn the mount about 20 minutes ago. I got the mail from Chromie, looted the mount, learned it, and mounted up. After logging out and to another character, I couldn’t find the mount in my collection. Logging back to the character I got it on, the mount was also missing there, despite being ON it. Once dismounting, I could no longer click the icon which I had moved to my action bars. Upon further looking, my Lil Nefarian pet is also missing, which I had learned before even doing the Anniversary content. I still have the achieve for earning the mount and the letter from Chromie as a result, but the mount and pet have both disappeared from my collection.