Traefik Ingress (Kubernetes) not receiving letsencrypt certificates
How are you injecting the letsencrypt config to your traefik Ingress service/daemonset?
Traefik doesn't officially have letsencrypt on Kubernetes Ingress docs. But this is a good guide. Look for "External Traefik ingress controller" and you need a kv backend to store your certs.
You can also try cert-manager which works with Traefik.
The built-in ACME support for Traefik is not recommended for use on Kubernetes at this time as setting up failover/redundancy becomes difficult. Cert-manager, as mentioned by Rico, is a better solution and is the one recommended by the Traefik team currently :)