"Edit Master Pages" in Pages is not working!

I want to edit Master pages in Pages. I followed the directions in Help,:

1. Click in the toolbar, then choose Edit Master Pages.

However there was no "Edit Master Pages" on the list when it appeared.

I did find a "Edit Master Pages" in the dropdown view menu but it was greyed out. No amount of clicking made it turn black/functional.

The key command for Edit Master Pages, Shift-Command-E, had no effect.

I've tried accessing this feature in multiple documents both new and old to no avail.

I'm running OS 10.15.6 on a MacBook Pro and this problem occurred with both Pages 10.0 and 10.1

HELP! I need to edit the master pages.