Two Factor Authentication Failed to be Enabled

Dear All,i have followed the instruction here Setup Two Factor Authentication
While in bench directory, I ran the command but I have this error that I should specify the --site sitename despite specifying the --site sitename
fred@vps282314:~/frappe-bench$ bench --site set-config enable_two_factor_auth true
Please specify --site sitename

Any pointer will be appreciated.

The instance is on ERPNext: v12.14.0 (version-12)

Frappe Framework: v12.12.0 (version-12)

The error message “Please specify --site sitename” persists despite specifying the sitename.Is there anything I am doing wrong or is it a bug?