Watchtower is not detecting new images in docker hub private repository

[aw94]

Describe the bug
Watchtower doesn't seem to find new images in my docker hub repository.

time="2020-06-14T19:38:24Z" level=debug msg="Pulling awif1570/test:1.5 for /elegant_ramanujan"
time="2020-06-14T19:38:24Z" level=debug msg="Loaded auth credentials for user awif1570, on registry awif1570/test:1.5, from file /config.json"
time="2020-06-14T19:38:24Z" level=debug msg="Got image name: awif1570/test:1.5"
time="2020-06-14T19:38:25Z" level=debug msg="No new images found for /elegant_ramanujan"

I started Watchtower like this from the terminal

docker container run -d -v /var/run/docker.sock:/var/run/docker.sock -v /root/.docker/config.json:/config.json containrrr/watchtower --debug --interval 30

My config.json

{
        "auths": {
                "https://index.docker.io/v1/": {
                        "auth": "auth-key"
                },
                "awif1570/test": {
                        "auth": "auth-key"
                }
        },
        "HttpHeaders": {
                "User-Agent": "Docker-Client/19.03.8 (linux)"
        }
}
~      

My latest image in my docker hub repository is called awif1570/test:1.6
Watchtower seems to be pulling 1.5 over and over because the download counter of that image keeps ticking up.
I've tried REPO_USER and REPO_PASS environment variables however I have the exact same issue.

To Reproduce
Steps to reproduce the behavior:

1. Run in terminal:

docker container run -d -v /var/run/docker.sock:/var/run/docker.sock -v /root/.docker/config.json:/config.json containrrr/watchtower --debug --interval 30

2. Push new image to docker hub registry with docker push

Expected behavior
Watchtower should detect and pull latest image

Environment

• Platform
  Ubuntu 18.04.3 LTS

• Architecture
  amd64

• Docker version
  Docker version 19.03.8, build afacb8b7f0

Logs from running watchtower with the --debug option

time="2020-06-14T19:38:24Z" level=debug msg="Pulling awif1570/test:1.5 for /elegant_ramanujan"
time="2020-06-14T19:38:24Z" level=debug msg="Loaded auth credentials for user awif1570, on registry awif1570/test:1.5, from file /config.json"
time="2020-06-14T19:38:24Z" level=debug msg="Got image name: awif1570/test:1.5"
time="2020-06-14T19:38:25Z" level=debug msg="No new images found for /elegant_ramanujan"

[github-actions[bot]]

Hi there! 👋🏼 As you're new to this repo, we'd like to suggest that you read our code of conduct as well as our contribution guidelines. Thanks a bunch for opening your first issue! 🙏

[simskij]

Hi, and welcome to the community! 🎉

Watchtower only updates on image changes for the same tag. The usual way to solve this is to have a :latest tag that you update with each release in addition to adding your versioned tag.