Well I’m not sure if it’s because 30m has passed since you posted this:
Or because I somehow altered state by doing this in your site’s console:
SiteSetting.theme_site_settings_json(-1)
=> "{\"enable_welcome_banner\":false,\"search_experience\":\"search_field\"}"
But yeah I saw that it was visible, ran that in the console, and then it was gone 
So definitely feels like this is a caching thing…