Process is missing from the Processes list
GNOME System Monitor 3.36.0
PopOS 20.04
After a restart the fans from my laptop started spinning, so I checked gnome-system-monitor, to see which processes are running, under resources it showed me that one core is running on 100% but under processes, no process was listed which was using so much cpu. Top and htop could show me the process.
Sadly I did not made a screenshot, but the process was gzip started with the root user and I guess it was triggered from tracker. Tracker was also running and using 11%, tracker was shown in both gnome-system-monitor and top/htop.