Only half of animation rendering when export to mp4

Hi all, I am fairly new to animate and had an issue when exporting my final scene to mp4. The produced MP4 comes back partially rendered. For example, the bottom half of the animation is working and then the top half just is not visible. Has anyone encountered this before or know if it sounds like there is a bug in one of the library objects? 

P.S. when I did test renders of the smaller items in my library that compromise this bigger animation, they all worked perfectly fine.... Just not all together