Activity Monitor No Longer displays columns

I have a Mac Mini (late 2012) running Catalina (10.15.3). I can't remember when I first noticed it, but for a while now, I cannot sort Activity Monitor's columns. This is essentially what it looks like:

I've tried to find some way if I can perhaps reset its preferences, but google is not my friend.

Can someone help?

You probably can just go to the View menu (the one between Edit and Window), select Columns and add additional columns again (or switch to a simple process view and back to hierarchical).

If this doesn't work, you can remove preferences by

• Quitting Activity Monitor
• rm ~/Library/Preferences/com.apple.ActivityMonitor.plist*