I am using Katalon Studio 7.1.2 on MacOS
Once I chose Katalon Studio > Preferences; then in the side-bar I choosed Katalon > Test Case. Did something and closed the dialog. This worked fine.
I called up the Preferences dialong once again. I saw the side-bar looked strange. I expect the side-bar to show a tree view always, but it shows “Test Case” only.
When I typed something in the “type filter text” fied, then the side-bar is restored to the ordinary tree view.