invalid reference format error in docker-image-resource put

Currently trying to build and push docker images, issue is that I'm receiving a this message from concourse during wordpress-release put step:

waiting for docker to come up...
invalid reference format

Here's the important bit of the Concourse Pipeline.

- name: wordpress-release
  type: docker-image
  source:
        repository: #############.dkr.ecr.eu-west-1.amazonaws.com/wordpress-release
        aws_access_key_id: #############
        aws_secret_access_key: #############
- name: mysql-release
  type: docker-image
  source:
        repository: #############.dkr.ecr.eu-west-1.amazonaws.com/mysql-release
        aws_access_key_id: #############
        aws_secret_access_key: #############
jobs:
- name: job-hello-world
  plan:
  - get: wordpress-website
  - task: write-release-tag
    config:
      platform: linux
      image_resource:
        type: registry-image
        source: { repository: alpine/git }
      inputs:
        - name: wordpress-website
      outputs:
        - name: tags
      run:
        dir: wordpress-website
        path: sh
        args:
          - -exc
          - |
            printf $(basename $(git remote get-url origin) | sed 's/\.[^.]*$/-/')$(git tag --points-at HEAD) > ../tags/release-tag
  - put: wordpress-release
    params:
      build: ./wordpress-website/.
      dockerfile: wordpress-website/shared-wordpress-images/wordpress/wordpress-release/Dockerfile
      tag_file: tags/release-tag
  - put: mysql-release
    params:
      build: ./wordpress-website/
      dockerfile: wordpress-website/shared-wordpress-images/db/mysql-release/Dockerfile
      tag_file: tags/release-tag

Those images contain FROM #############.dkr.ecr.eu-west-1.amazonaws.com/shared-mysql (and shared-wordpress) could this be an issue?

The tag_file: tags/release-tag, doesn't seem to be the issue as even without it, this still happens.

This is Concourse 5.0 running on top of Docker in Windows 10.

Start by reproducing the docker-image-resource put with the provided Concourse pipeline, ECR repository names, Dockerfiles, and tag_file settings on the stated Concourse 5.0 and Docker-on-Windows setup. Inspect the resource and Docker output around “waiting for docker to come up” and “invalid reference format”; done means identifying the malformed reference or confirming a minimal reproducible failure.