Steps to replicate the issue (include links if applicable):

• Delete the page MediaWiki:CampaignEventsConfig.json if it exists
• Go to Special:CommunityConfiguration/CampaignEvents
• Confirm that the Project namespace is listed
• While logged in with a valid organizer account, create a page in the Project namespace

What happens?:

• The "enable registration" header isn't shown
• Trying via Special:EnableEventRegistration, it complains that the page is not in the Event namespace

What should have happened instead?:

• The header should be shown and it should be possible to enable registration for that page

Software version (on Special:Version page; skip for WMF-hosted wikis like Wikipedia):
master

Other information (browser name/version, screenshots, etc.):
Overriding the setting in CommunityConfig will fix this. It's just the default value that doesn't work.