{!URLFOR($Action.CustomObject__c.List, $ObjectType.CustomObject__c)}
is not working within a community whilst logged in as the community user.
The page loads but onto the 'Invalid Page'. This operation works just fine from within SF itself, When doing it as the admin on the community the page loads but you must login again first.
I have updated the community user to user a different licenese and profile and the issues still happens.
The Org type is a Development Org, if that helps in anyway