Objects disappears in my animation

Hello everyone, I am working on a new project where I have animation. It is an industrial project where I have a crane that moves objects … I have a slight problem with the animation, I did my animations under 3dsmax and I exported in FBX, then I imported the skeletal mesh. The animation works well
however some objects disappear from time to time according to the direction in which I look. If I focused on these objects they never disappear, but if I put them in a corner of my screen it disappears sometimes. I partially solved the problem by following this answer : https://answers.unrealengine.com/.../my-animation-pausesdoes-… But I still have an object that disappears. I put 2 screenshots to illustrate the problem.
I had already encountered this problem on an old test I had done on animated characters, but I had not dug the question at that time …
Thank you for your help!