[Solved] Syslog full of "unknown container" warnings for existing container

Hi there,
I am having a lot of log entries in syslog for unknown containers:

dockerd[645]: time="2018-01-22T14:36:47.387239883+01:00" level=warning msg="unknown container" container=65c5ea981f0bd1c136faf23b9d0ec9e8df51065ee8991783ecc701675c8e84c8 module=libcontainerd namespace=plugins.moby

However the container exists and is running.
An clue on how to debug this or get rid of the warning (it is appearing multiple times per second)?

Docker Info:
Containers: 4
Running: 4
Paused: 0
Stopped: 0
Images: 4
Server Version: 17.12.0-ce
Storage Driver: aufs
Root Dir: /var/lib/docker/aufs
Backing Filesystem: extfs
Dirs: 48
Dirperm1 Supported: true
Logging Driver: json-file
Cgroup Driver: cgroupfs
Volume: local
Network: bridge host macvlan null overlay
Log: awslogs fluentd gcplogs gelf journald json-file logentries splunk syslog
Swarm: inactive
Runtimes: runc
Default Runtime: runc
Init Binary: docker-init
containerd version: 89623f28b87a6004d4b785663257362d1658a729
runc version: b2567b37d7b75eb4cf325b77297b140ea686ce8f
init version: 949e6fa
Security Options:
Profile: default
Kernel Version: 4.9.0-5-amd64
Operating System: Debian GNU/Linux 9 (stretch)
OSType: linux
Architecture: x86_64
CPUs: 2
Total Memory: 15.61GiB
Name: diskstation
Docker Root Dir: /var/lib/docker
Debug Mode (client): false
Debug Mode (server): false
Registry: https://index.docker.io/v1/
Experimental: false
Insecure Registries:
Live Restore Enabled: false

WARNING: No swap limit support

Found an existing Issue: https://github.com/moby/moby/issues/35891

Fix is on the way