The mysterious case of Touch Bar options - Why did they disappear and reappear in System Preferences?

I have a Macbook Pro 16" 2019 running macOS Catalina.

I am wondering what controls the visible / invisible status of the Touch Bar settings (i.e. Touch Bar shows ..., Press Fn key to ..., and Customise Control Strip ...) as shown in the red boxes in the second screenshot.

So my story is, I recalled today there should be some Touch Bar settings in the System Preferences, but I couldn't find them initially (as shown by the first screenshot). After some random clicks and attempts (without restarting the computer), the options mysteriously reappeared (as shown by the second screenshot).

Could someone please explain to me, what possibly caused these Touch Bar options to appear and disappear?

(I am using an Apple Magic Keyboard in the meantime. Not sure if this is related.)

Solution 1:

Touch Bar settings are hidden when the computer is in clamshell mode (closed), as the Touch Bar is not accessible.

To make them reappear:

• Open the lid of the MacBook
• Quit System Preferences
• Re-open Keyboard settings