@Izerix
That is Because the Harpy used to have 4 frames pre 1.4, and in 1.4 The harpy have 6 frames
I assume this is a "Xnb replacement" texturepack?
as a 1.4 Texturepack should do something like that, the file should not be lodaded if it doesn't have the right Dimentions. unless it was in incable hands or sabotaged on purpose...
But you probably should ask or mention this on their
Discord, as they don't seem to be using this forum much
aside saying "Please join our discord for help and newest version"