Greetings Andy,
I disabled all the plugins except woocommerce. The discussion option appeared and its appearance is linked to the Disable Comments function as you thought, but the sidebar layout option never appeared. I copied them below and bolded the ones that are checked.
Page Attributes
Featured Image
Header
Client Logos Section
Title or Full Screen Slider/Hero
Slider/Hero Section
Excerpt
Custom Fields
Discussion
Slug
Author
Custom CSS
Layout 2 columns
Enable full-height editor and distraction-free functionality.
Ivette