"no valid plugins were enabled" reported by sosreport while running as root

Issue

• Executing sosreport as the root user reports that no plugin is enabled

  # sosreport
  
  sosreport (version 3.7)
  
  no valid plugins were enabled
  

• There is no customization of /etc/sos.conf that could explain the issue

  [general]
  #verbose = 3
  #verify = yes
  #batch = yes
  #log-size = 15
  
  [plugins]
  #disable = rpm, selinux, dovecot
  
  [tunables]
  #rpm.rpmva = off