this keeps happening and I have no idea what to do. This is with any animation I try and use.
I am having the same issue and it is due to the fact that the animation pack that I downloaded uses a different skeleton and mesh to the character that I try to play the animation on.
Basically you have to change the skeleton that the animation tries to use.
https://answers.unrealengine.com/questions/440892/change-skeleton-asset-of-animation-bp.html