It is a bug of Webmin 1.941 on Ubuntu 20.04 LTS.

There is no Running Processes information on the home page or System Information page.

Then, I google it and find the solution on the Webmin/Bugs page.

I did the fix as below:

1) SSH to the Ubuntu Server.

2) Backup the old file.

cd /usr/share/webmin/proc/

sudo mv linux-lib.pl linux-lib.pl.1.941

3) Add the new linux-lib.pl

sudo nano linux-lib.pl

Add the content from the link below into it and save it.

linux-lib.pl

4) Done. Check the webmin panel.

And If check the details of the running processes. It shows the list of the processes instead of the empty page.