Docker - "repository name must be lowercase" error

I’m trying to use the aws-ecr/push-image task to push an image built by my build but I keep seeing this error - repository name must be lowercase. I tried checking the name of the repository as well as all other parts that go into building the repo url. They are all lower case. Has anyone faced a similar issue? Here is the relevant part of my config file -

- aws-ecr/push-image:
    repo: my-service