I can't learn the shout to call Odahviing from Parthurnax. The questline procedes as if I had learned the shout, but I did not actually learn the shout. This is my second playthrough that I've got this far, and the first time, I learned it without a problem.

I'm currently at the point where the Blades won't talk to me if I don't kill Parthurnax, so they won't help me, either.

I'll need to experiment to see if I can even kill Parthurnax, because I'm well aware of that glitch.

After leveling to 55, acquiring every daedric artifact I know of, becoming guildmaster of mage, thief and companion guilds (as well as the Volkihar), experiencing only a few sidequest and Dawnguard glitches involving Serana and LeTrush... After all this, the main quest could be a potential dead end?

Fortunately, I've kept a save right in front of Paarthurnax before even talking to him so I can experiment with this folly. Any ideas?