I just beat the Stalker Spec and made it to level 70. As I went to go start a new specialization, they were all missing except the 2 I completed (Operator, Stalker) and Wetwork. I got my specializations through the Specializatio Priority Alpha thing. Is this a glitch?
Just reboot the game or download the specialization again from your download history.
Something similar happende to me aswell.
I had to download all the Halo 4 LE items again. (Helmets, Specializations etc.)
You can do this at Xbox Dashboard.