Can’t execute Durnehvirr's shout [duplicate]

I have a problem with Durnehvirr's shout. I’ve unlocked all three words of the shout, but the shout won’t execute, no matter how long I hold down the z before release.

Also, the quest “Learn the first word of Durnehvirr's shout” remains as incomplete in the miscellaneous quest tab, even though, as I’ve said, I’ve unlocked all three words. Not gonna reload previous save cause I’ve basically finished a bunch of stuff before I noticed this problem.

As the comments indicate as well:

Durnehviir is technically a summoned creature, unlike Odahviing; therefore, the shout can only be completed while pointing at a suitable location for a summoning, such as the ground.
This also means that you can summon him within certain enclosed areas, such as caves, as long as there is enough room.

I.e. summoning him works like a Conjuration spell. Make sure there is sufficient space for the entity to spawn.

As to the problem with your quest not updating:

The miscellaneous quest "Learn the first word of Durnehviir's shout" is actually referring to Soul Tear, an entirely different shout that Durnehviir will teach to the Dragonborn, one word at a time, during his first three summonings.

So in order to complete this, you will have to summon Durnehviir. He will then teach you the first word.

The procedure you need to follow is also illustrated in this video (from 0.00 to 1.12).

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