Great to meet a colleague here on the Forum.
Assuming you are just using the default Atlas DesignSystem, this should be the behaviour: https://atlasdesignsystem.mendixcloud.com/p/layout-default
As I see in your screenshot it is not. In the question, you mention Mendix StudioPro 10.3.1. I tested it just now, and I have the proper behaviour. But you also mention Studio Pro. This is discontinued since 9.20 if I remember well.
This is the 10.3.1 view:
We can have a look in the office and under the hood at what is causing the problem.
For the learning path, you can continue knowing you didn't do anything wrong.
Go Make It