Activity Monitor does not show values

Hello! Please try this:

1. Close the Activity Monitor if it's open
2. Open the finder
3. In the taskbar, press "Go", then press "Go To Folder"
4. Enter "~/Library/Preferences/com.apple.ActivityMonitor.plist" without the quotation marks
5. This should open the Preferences folder where "com.apple.ActivityMonitor.plist" is selected
6. Move the file to the trashcan
7. Open the Activity Monitor again, and check if the columns are there

If you were to have any further questions, don't hesitate to ask!

Regards,

Alexander

[Edited by Moderator]

Boot into Safe Mode (How to use safe mode on your Mac - Apple Support) by booting with the Shift key held down and check there to see if the problem persists.  Reboot normally and test again.

NOTE: Safe Mode boot can take up to 10 minutes as it's doing some system cache cleaning, volume verifying and directory repairing.