Passing issue along.
Your problem must be with Dreugh King Slayer because i just poped a major expedition potion in werewolf form, and not only does the buff registers in my tracker but move speed is visibly increased.
Well, I respecced the morph to Hircine's Fortitude, and guess what? I got my Major Expedition back after kills. So I'm guessing the bug lies within the coding for Hircine's Rage.
Another (hopefully just a) bug I noticed: After respeccing Hircine's, I went to a public dungeon to level it up. Well, after a whole hour of wolfing, the skill level bar is still at zero. Hopefully just a graphic bug, and not an hour wasted with no skill leveling.