I got Windows10 and have downloaded Quicktime 7.7.9 and trying to export a Movie in Harmony essential.
It doen´t work, nothing happens.
I had the same problem. This worked for me:
Try opening Harmony in Windows as an administrator (right click on the Harmony icon, more > run as administrator).
Another thing that I encountered was that I couldn’t change the Quicktime codec to anything else than h264.
I contacted support, and they said it’s a bug and they’re working on it…