Elements into view trigger animation not working consistently!

I made the elements in my portfolio fixed position. I added scroll into the view animation on each section so when the section is scrolled into view, a out of view animation will hide the previous section’s content and show the next section.

Here is how it suppose to work usually.

The problem I encountered is that the out of view trigger is inconsistent. It sometimes lags and bugs out and does not hide the previous section. Does anyone know how to prevent this?

Here is when the bug appears.

Here is my public share link: [LINK][1]

[1]: http:// Webflow - chenkangwu