Dockerfile builds on linux/mac host OS, but not on Windows 10 - powershell

Question

I have the following Dockerfile for a django app:
FROM python:3.6
RUN mkdir /server
WORKDIR /server
RUN apt-get update && apt-get upgrade -y && apt-get install -y \
libsqlite3-dev
RUN pip install -U pip setuptools
RUN pip install --upgrade pip
COPY requirements.txt ./
RUN pip install --no-cache-dir -r requirements.txt
COPY . .
WORKDIR /server/django
ENTRYPOINT ["/bin/bash", "../docker-entrypoint-server"]
relevant docker-compose related to it:
version: '3'
services:
server:
build: .
container_name: server
environment:
SERVER_ENV: ${SERVER_ENV}
DB_AUTH_SOURCE: ${DB_AUTH_SOURCE}
DB_NAME: ${DB_NAME}
DB_HOST: ${DB_HOST}
DB_USER: ${DB_USER}
DB_PASSWORD: ${DB_PASSWORD}
networks:
- app
ports:
- 8081:8000
volumes:
- .:/server
command: /bin/bash
tty: true
stdin_open: true
they work like a charm on linux/mac, but not on Windows 10. When the build reaches the COPY instruction, all it copies are the directory and only the first nested directory within it with no content attached to it.
tried to check for the shared C:\ option on docker, didnt work.
tried on powershell with admin rights and nothing.
What could be the possible causes? Why it works on two host OS and not on Win 10?
edit 1: versions
Windows: Windows 10 Education, 1803
Linux: Ubuntu 18.03 LTS
Mac: High Sierra 10.03
Docker: latest version on all OSs
edit 2: the solution
Turns out that unsharing and sharing, pointed out by JDPeckham, revealed the problem: a firewall misconfig caused by an antivirus that was controlling these configs.
This article: https://success.docker.com/article/error-a-firewall-is-blocking-file-sharing-between-windows-and-the-containers is very helpful for troubleshooting those.