I recreated the problem on my Windows 10 machine. I installed windows drivers and the firmata and restarted. Maker App did not see the board although my computer did see the board. I went to code.studio in Chrome (lesson 3 activity 4) just as one further troubleshooting attempt and Chrome sees my board. Perhaps the same is true for you? Can you (or your students) try the boards in Chrome? If this step doesn’t work, it would be best to reach out to http://support.code.org/ for support.
Michelle