Spritesheet incomplete

Hi Everyone! So I import animations from After Effects to animate, in order to generate the spritesheets but sometimes the spritesheet is incomplete. When this happens, I usually add at a corner of my composition, a tiny animation of an object moving while changing color. It usually works as a litttle trick, though later I have to erase it in photoshop.. but now, I have an animation where it absolutely wont give me the spritesheet complete, it'd give me like half of the animation and idk what to do. Could someone help me?