Why does this happen when using animations from Blender

Hi there,

First of all, I'd like to say I am relatively new to animating and modelling so forgive me if this seems trivial.

My issue is that I've made a simple animation for a fishing rod using key frames/blendshapes from Blender. It appears correct in Blender but causes stretching to the mesh in Unity.

Blender:


Unity:


Any guidance or feedback would be greatly appreciated. Thanks all!