contrib/check-config.sh shows cgroup hierarchy: nonexistent?? with cGroups v2

Steps to reproduce the issue:

1. Use cGroups v2 on Ubuntu 20.04
2. Use the contrib/check-config.sh script to check your ocnfiguration

Describe the results you received:

The cgroup hierarchy is shown as nonexistent.

Describe the results you expected:

cGroup hierarchy should be working (?)

Additional information you deem important (e.g. issue happens only occasionally):

I'm not a professional when it comes to cGroups. Maybe my setup is wrong.

Additional environment details (AWS, VirtualBox, physical, etc.):

None I deem important at the moment.