Page sorting in panel

Hello, I am wondering if the pages in the panel can be sorted by a custom field. I followed the docs and this is the important part:

title: News Details
icon: 🔖
num: '{{ page.newsdatestart.toDate("Ymd") }}'
      label: Datum
      type: date

But this does not seem to sort the pages in the panel. Screenshot where i added the title of the dates in question:

As this site is gonna have a million of these pages, it would be nice if they are sorted in the panel?

Actually works, just had to update blocks inside of existing pages so that content would be renamed.