[knot-dns-users] DNS cookie not configured correctly?

Hi, i have knot dns setup with dns cookie module enabled but if i check with dnsviz.net i always get: The server appears to support DNS cookies but did not return a COOKIE option. Relevant parts of my knot.conf: template: - id: default storage: "/var/lib/knot" dnssec-signing: on dnssec-policy: rsa2048 global-module: [ "mod-cookies", "mod-rrl/default" ] mod-rrl: - id: default rate-limit: 200 slip: 2 - domain: mydomain.de file: "/etc/knot/zones/mydomain.de.zone" notify: secondary acl: acl_secondary zonefile-load: difference I thought about maybe it's the slip: 2, but that didn't change anything if set to 1 Do you guys see anything obvious causing this "issue"? Thanks for your time Juergen