Okay Let me be more specific.
Check my codepen now I have updated time from .2 to .7 in animations[0], animations[1], animations[2] all the three slides. You can find that time in updated code is .from('.section1 .portfolio-inner-image',.7,{yPercent:100})
Now you can see the scroll animation issue from 2nd slide. 1st slide animation is working fine which have blue background but the 2nd slide animation(orange background) not working properly is showing visibility hidden, opacity 0 instead of visibility visible, opacity 1.
If I will change this .7 to .2 .from('.section1 .portfolio-inner-image',.7,{yPercent:100}) in all slide then it will work fine as you saw before.
Let me know If still you are not getting my point then I can send you video of the issue.