Problem

When navigating to Administration > System > Advanced Settings

Diagnosis

1. HAR file looks good.
2. Enabling safe mode didn't help
3. It is showing a blank page regardless of what browser is in use or even in incognito mode.
4. Not user (admin) specific.

Cause

In jpm.xml file, all the lines with <admin-editable>true</admin-editable> where all the advanced configuration options are located is removed.  

Resolution

Adding back the lines with <admin-editable>true</admin-editable> should show the Advanced Setting options.