Are you trying to use Repeater but don't want the repeated shapes to fade on, but instead appear instantly?

I too was facing this issue and wanted to share a solution I found that was much simpler than other threads I’d read.

I noticed that when the distance between keyframes was more than the number copies I was making the copies value would add a decimal place, which affected the opacity of the copy. So, under Copies I added a “Math.round()” expression making the value stay whole numbers and now I can move the keyframes around and it doesn’t affect the opacity of the copies animating on at all. 

I hope this helps!