Can't reset BIG-IP to factory defaults

Yes seems to verify:

root@(localhost)(cfg-sync Standalone)(Active)(/Common)(tmos) load sys config verify
Validating system configuration...
  /defaults/asm_base.conf
  /defaults/config_base.conf
  /defaults/ipfix_ie_base.conf
  /defaults/ipfix_ie_f5base.conf
  /defaults/low_profile_base.conf
  /defaults/low_security_base.conf
  /defaults/policy_base.conf
  /defaults/wam_base.conf
  /defaults/analytics_base.conf
  /defaults/apm_saml_base.conf
  /defaults/app_template_base.conf
  /defaults/classification_base.conf
  /defaults/daemon.conf
  /defaults/profile_base.conf
  /defaults/sandbox_base.conf
  /defaults/security_base.conf
  /defaults/urldb_base.conf
  /usr/share/monitors/base_monitors.conf
Validating configuration...
  /config/bigip_base.conf
  /config/bigip_user.conf
  /config/bigip.conf
root@(localhost)(cfg-sync Standalone)(Active)(/Common)(tmos)

We're on v11.6. Many thanks.