Just twist the cap counterclockwise a little harder. It will make a little click and then turns freely. There is some initial resistance as the 'hole in the middle' is an indentation that keeps the cap from turning unnecessarily.The cap does NOT turn. It has a post in the middle that matches a hole in the reservoir.
Hmm, possible they 'child-proofed' the 2012 cap?Maybe it needs to be pushed in first before turning counterclockwise. Simply turning it will keep it locked. ? Some of my caps are this way.