Docker push to self hosted private registry fails with message "no basic auth credentials"

Question

I'd like to push images from my docker-client in WSL2 to my self-hosted docker-registry which is running on kubernetes in my local network.

After setting up the registry, I get a "no basic auth credentials" when trying to push to or pull from the registry. On my client, I have configured docker to use pass and the docker-credential-helper (v 0.6.4) as the credentials-store.

Here is an example of a failed attempt trying to connect and push to the registry:

ubuntu@X:~$ cat .docker/config.json
{
        "auths": {},
        "credsStore": "pass"
}

ubuntu@X:~$docker login kubernetesmaster:30000
Username: ubuntu
Password:
Login Succeeded

ubuntu@X:~$ cat .docker/config.json
{
        "auths": {
                "kubernetesmaster:30000": {}
        },
        "credsStore": "pass"
}

ubuntu@X:~$ docker-credential-pass list
{"kubernetesmaster:30000":"ubuntu"}

ubuntu@X:~$ docker push kubernetesmaster:30000/postgres:14.1-alpine3.15
The push refers to repository [kubernetesmaster:30000/postgres]
84c1bdf77e22: Preparing
176b9203da6e: Preparing
efb18f6577c9: Preparing
6c651825e7c4: Preparing
be6c168b4af5: Preparing
b737c2580132: Waiting
6cab14f8a434: Preparing
8d3ac3489996: Preparing
ERRO[2021-12-12T09:39:07.873814200+01:00] Upload failed: no basic auth credentials
ERRO[2021-12-12T09:39:07.873821500+01:00] Upload failed: no basic auth credentials
ERRO[2021-12-12T09:39:07.873796800+01:00] Upload failed: no basic auth credentials
INFO[2021-12-12T09:39:07.874817900+01:00] Attempting next endpoint for push after error: no basic auth credentials
6cab14f8a434: Waiting
no basic auth credentials

ubuntu@X:~$ docker pull kubernetesmaster:30000/postgres:14.1-alpine3.15
INFO[2021-12-12T09:39:15.293957000+01:00] Attempting next endpoint for pull after error: Head "https://kubernetesmaster:30000/v2/postgres/manifests/14.1-alpine3.15": no basic auth credentials
ERRO[2021-12-12T09:39:15.301905100+01:00] Handler for POST /v1.41/images/create returned error: Head "https://kubernetesmaster:30000/v2/postgres/manifests/14.1-alpine3.15": no basic auth credentials
Error response from daemon: Head "https://kubernetesmaster:30000/v2/postgres/manifests/14.1-alpine3.15": no basic auth credentials

ubuntu@X:~$ docker --version
Docker version 20.10.11, build dea9396

Note: The login works with docker-login, pushing and pulling just seems to use some bad credentials. I'm a bit stuck here. Help would be much apprechiated!