I had to take my car in twice for the exact same problem. The first fix was to bleed the system to extract any air pockets. The ticking stopped for about a month. When I brought it in again, they ended up replacing the head. The new head has an integrated check valve that allows easier oil flow to the lifters. It's been a month and still no noise. I did start getting a burning plastic smell through the vents from time to time and after 2 weeks of bringing it back and forth to the dealership, they finally figured out that the valve cover gasket needed to be replaced since oil was leaking.