Is this the whole result?
I get this:
/etc/sudoers: parsed OK
/etc/sudoers.d/10_nethserver: parsed OK
/etc/sudoers.d/20_nethserver_backup_config: parsed OK
/etc/sudoers.d/20_nethserver_base: parsed OK
/etc/sudoers.d/20_nethserver_dc: parsed OK
/etc/sudoers.d/20_nethserver_httpd_admin: parsed OK
/etc/sudoers.d/20_nethserver_mail_common: parsed OK
/etc/sudoers.d/20_nethserver_mail_server: parsed OK
/etc/sudoers.d/20_nethserver_sssd: parsed OK
/etc/sudoers.d/40_nethserver_restore_data: parsed OK
/etc/sudoers.d/90_nethserver_nextcloud: parsed OK
If yes check the last line of /etc/sudoers
, it should be #includedir /etc/sudoers.d
.