Impossible to customize controls while in Spectator mode

Steps to reproduce:

1. Create/open a world
2. Switch to Spectator mode: /gamemode spectator
3. Enable Customize Controls (Experimental) in Settings -> Controls -> Touch
4. Attempt to press Customize controls in Settings -> Controls -> Touch

Observed result:
You are unable to customize controls while in Spectator mode. Pressing the info button shows a pop-up that says "Load a world to customize controls", despite already being in a world.

Expected result:
You are able to customize controls while in Spectator mode.