Fixed Modal Scrolling

Hi all,

This is potentially a daft issue, but I cannot figure it out at all.

So I’m building a one page site, controlled by interactions:
Click thumbnail, close thumbnail section, open new modal with more info, close modal re-open thumbnail section.

However, when I have my new modal set to “fixed” where I want it to be, so that it always opens to the correct point no matter where the site is scrolled to. I can’t scroll on that modal?

Sure it’s something I’ve clicked and not realised but I just can’t seem to find it.

Here is my site Read-Only:
([how to share your site Read-Only link][2])