ACME certificates not created for dashboard only with swarm [Traefik 2.2.0]

Hello all,

With this configuration there is no exchange at all for dashboard certificat

    deploy:
      labels:
        - "traefik.enable=true"
        - "traefik.http.routers.api.rule=Host(`traefik.xxx.fr`)"
        - "traefik.http.routers.api.service=api@internal"
        - "traefik.http.routers.api.entrypoints=https"
        - "traefik.http.routers.api.tls=true"
        - "traefik.http.routers.api.certresolver=xxxx"
        - "traefik.http.routers.api.middlewares=auth"

The certresolver works well with all my websites, except api

Debug:

time="2020-04-30T13:33:44+03:00" level=debug msg="Adding certificate for domain(s) e2guardian.xxx.fr"
time="2020-04-30T13:33:44+03:00" level=debug msg="Adding certificate for domain(s) nas.xxxx.fr"
time="2020-04-30T13:33:44+03:00" level=debug msg="Adding certificate for domain(s) portainer.xxxx.fr"
etc

As you can see there is no DNS-01 request at all for my dashboard domain (of course well resolved by DNS)

Dashboard is enabled in traefik.toml

[api]
   dashboard = true

What I missed ?

Regards