How come we never saw Dragons leaving the body of the Dragon Slayers in Fairy Tail (2014)? We don't see the Dragons leaving the body of the Dragon Slayers except in Natsu's case, even though Igneel mentioned it in Episode 89. Why is that? Did they forget to animate it?

[Edit- Note :If they have not mentioned it in manga then wouldn't that will be a plot hole because everybody will be aware of the dragons leaving the dragon slayers body and no one would have been surprised to see the face getting destroyed at that time. Also fighting Achnologia would have been much easier.]
As far as I know, all Dragons of 1st and 3rd generations Dragon Slayers had shown themselves in the anime. Igneel againts Acnologia, while the other 4 (Metallicana, Grandine, Weisslogia, Skiadrum) helped in destroying Face.