Scroll Snap - Need help

I need some help understanding the “Scroll Snap” feature for Layout Blocks.
Nothing explicit in the documentation and it does not behave as I would expect.
For one thing, it ignores completely the “Scroll Location” anchor I give it.

So. Any help understanding how it is supposed to work, or how best to use it, or even if it is currently broken would be helpful.

tanks

Bueller?
(you know, from Breakfast Club…)