Mass Assignment Goals section - inconsistency in screen display

We are currently preparing the launch of the performance evaluation campaign including the use of mass assignment of goals. What we have noticed is the following behaviour.

While creating the mass assignment via "Setup of Performance Goals Mass Assignment and Mass Sharing", we have 2 possibilities

1. Adding the details and Goals at the same time - a panel right window will open on the right side:

2. Creating the mass assign process only with details, save it and then come back to add the goal. The difference is that when adding on the Goals now the system will no longer propose the right panel window but the New Goal page as per design displayed for self service.