Hello we are facing the same problem I think. on a couple days ago, I had the problem like you.
I've already search in stackoverflow and the skrollr github itself. and then I realize that in skrollr github said that you can't have position: fixed
.
So try to change your code instead of using data-center="background-position: 0% 0px;"
try change it with data-0-bottom-top="background-position: 0% 0%;
change your "px" with "%". I think (I still assume it) that "px" will define as fixed position, and we don't want the fixed position.
And don't use fixed background-attachment on your css.
this is my sample project you can find it here.
I hope this answer can help. Thank you.