Animation problem

I have a problem with my animation.

As You can see everything looks ok until frame 360 - triangles are disappearing.
But after that frame there is a shape that dont dissapear and everything seems to be going on behind this shape.

Thanks for Your help.

it’s hard to understand what you want to achieve in the first place

I don’t see a frame number, I don’t see what looks ok and what doesn’t, I don’t see the shape that’s supposed to disappear and I don’t see what’s going on. Please describe what you want to do, where it goes sideways, add a frame number onto your sequence, and then hopefully we’ll be able to help !