It is weird and I tried out a lot to solve this - but without knowing what's wrong where, it's hard. I put the slider to an entirely new place without nesting it, cleared the content of both slides or just one, changed all kinds of properties, swapped slides (then the former 2nd slide is visible, the now 2nd not)...
The problem is, the slide after the first is way out of place. Changing slides, you just get the slider's mask to see, not the second slide:
That's the project's editing link: https://preview.webflow.com/preview/johanness-fantastic-proje-280ae17fb48db?preview=a79c24fca6beb4a45a1b4af1a513ee3a
Finding a solution to this would be awesome.
On another note webflow team, you've created an amazing and intuitive service. I learned it lightning fast, and I can't even code!