No First Person Animation

[Omega_5]

I'm running in to an issue with my melee ability. The animation plays fine in third person view, however it doesn't play in first person view.
This has happened to me a few times on other abilities, and I've had to re-build the ability from the start.
I'm curious as to what causes this. Is it something I randomly miss during setup? Or a conflict with the animator, maybe?

Edit:
Note, I'm using the demo animations, for now. I've seen a lot of topics that point toward the FPS Mesh tool, so I just wanted to clarify.

 

[Omega_5]

So, for anyone that comes across this issue; double check the Animator Controller on the FirstPersonArms.
I was so fixated on the main Animator Controller, that I forgot to update the slot parameters on the other one; hence the issues in the gif.