Freeze y-Position

Principle Version: 4.7
macOS Version: 10.12.6
Sketch Version: 51.3

Hi, I try to create an onepager with an menu to slide gently over the topics. When I link the buttons to the green boxed screen it scrolls exactly there in most cases. I found out to control this I have to default the y-position while animating. But in some cases there isn’t this option given. On this sites I also can’t scroll down but the settings are the same as where it works perfectly.
I hope you understand the problem.

Greetings Therese