Model seperates on loop

I have a model of a zombie in .fbx format, created in in Cinema 4D.

it is animated, frames 5 to 40 are the walking animation. I’ve attached it to a prefab along with an AI script and given it a character controller. now, when it walks every time the animation loops the arms just explode outwards for one frame. (screenshots below)

Now, it is important to note that the model/animation treats the arms as a separate part so I can use them as the collision area during an attack animation so the player doesnt get hurt if the arms don’t connect with him. I think this is partly the cause but I need them seperated this way.

any idea what is causing this and how to stop it from happening?


I still would like to know the real reason this happens but I have found the cause and removed it. Clicking on the animation importer for the zombie model in project view opens it up in Inspector view, when setting the ‘split animations’ I set the walking animation to loop AND clicked the loop checkbox. I am not entirely sure what the loop checkbox does but having that unchecked and the dropdown set to loop makes it loop without the arms exploding outwards.