Passing build-args to docker from secrets [v0.8.6]

Drone Support
1

Hello. I have been struggling with passing build args to docker from secrets that are passed. I have gone through so many of the same posts here and tried each one I read. Nothing is seeming to work. I have drone v0.8.6.

This is my .drone.yml file

pipeline:
  publish_image_to_ecr:
    image: plugins/docker
    repo: redacted.dkr.ecr.<region>.amazonaws.com/<repo-name>
    registry: redacted.dkr.ecr.<region>.amazonaws.com
    tags:
      - "${DRONE_COMMIT_SHA:0:7}"
      - latest
    secrets: [ecr_access_key, ecr_secret_key, npm_token]
    build_args_from_env: [NPM_TOKEN]
    when:
      event: push

I have added the secrets using the cli.
drone secret ls <repoName>

ecr_access_key 
Events: push, tag, deployment
Images: <any>

ecr_secret_key 
Events: push, tag, deployment
Images: <any>

npm_token 
Events: push, tag, deployment
Images: <any>

I am just trying to debug my container so my Dockerfile is only 2 lines

FROM alpine
RUN env

This returns the environment variables but there is no NPM_TOKEN stored over there.

If it helps the docker build command when the pipeline gets executed is as follows:

+ /usr/local/bin/docker build --rm=true -f Dockerfile -t 00000000 . --pull=true --label org.label-schema.schema-version=1.0 --label org.label-schema.build-date=2019-06-20T17:24:22Z --label org.label-schema.vcs-ref=00000000 --label org.label-schema.vcs-url=
2

I have also tried using build_args instead of build_args_from_env. The .drone.yml file looks like this

...
secrets: [ecr_access_key, ecr_secret_key, npm_token]
    build_args: [NPM_TOKEN]
...

This makes a change when the docker build command is run by the plugin

 + /usr/local/bin/docker build --rm=true -f Dockerfile -t 00000000 . --pull=true --build-arg NPM_TOKEN --label org.label-schema.schema-version=1.0 --label org.label-schema.build-date=2019-06-20T17:41:07Z --label org.label-schema.vcs-ref=00000000 --label org.label-schema.vcs-url=

As you can see the --build-arg has come but there is no value attached to it. How do I assign the value to the build arg? Or am I completely in the wrong zone about this?