I spent almost an hour trying to figure this out. So, I’m sharing the information in case someone else encounters the same issue.
I created a new game with 2 objects, added the platformer behavior and disabled the Default controls option. However, they keys didn’t work at all.
The solution was very trivial: I created conditions and actions within the same event. So, it would only work if I simultaneously press all 3 keys.
Here is the correct configuration:
The experiences users may say that I didn’t read docs/watch tutorials. And it is true. The program gives feeling that you can start creating games so easily that you don’t need to watch the tutorials or read the docs until that is necessary. I had to do that anyway while trying to figure out the issue. But I hope it will help someone else.