Hazel 5 doesn't remember which sidebar categories were expanded when the app is closed and re-opened.
Here's a screencast demonstrating this:
https://www.dropbox.com/s/369yqz18bri5z ... 1.mp4?dl=0
One other thing: this is my personal opinion, however I think that if you want to delete a category by clicking the round "-" button to the right of its name, a confirmation dialogue should be displayed. I was not at all prepared for the category to just vanish immediately the first time I clicked the button.