docker doesn't put files into the expected mounted folder

I have Dockerfile that looks like this

FROM python:3.7-alpine
VOLUME /folder
ADD my_packge.whl .
RUN wget -O- "" | tar -zx -C /usr/local/bin && \
    apk update && \
    apk add --virtual deps gcc python3-dev linux-headers musl-dev libffi-dev openssl-dev && \
    apk add --no-cache bash && \
    pip install my_package.whl && \
    apk del deps
ENTRYPOINT [ "python_app" ]

And I execute it like this

docker run --rm \
        -v ${WORKSPACE}/TEST_RESULTS:/folder \
        -e CF_USERNAME=${CF_USN} \
        -e CF_PASSWORD=${CF_PWD} \
        container/${CF_SPACE}:${GIT_TAG_NAME} \
        -b 'myy_parameter'

I expected that the execution results will put some files into ${WORKSPACE}/TEST_RESULTS. But it doesn't happen.

What is wrong?