Under "power management" I have
- Put computer when inactive for: Never
- When laptop lid is closed: Suspend
- Put display to sleep when inactive for: 30 minutes
this used to work under 19.10. I've upgraded to 20.04 (Focal Fossa) and now if I leave the laptop plugged in and walk the dog, the laptop is asleep when I return. If I push the power button it resumes, but I don't want it to sleep when plugged in.