auto open of downloaded dmg files in Sierra fails

My app has successfully been downloading, and auto opening, zipped dmg files. With the last Sierra update, this stopped.

I really need this. I have two zipped apps for sale online, that normally open the zipped dmg. Then then enclosed file is copied to the desktop, double clicked, and they auto install.

Now the user has to scramble through the downloads folder, and manually open the dmg.