Use the dropzone widget from the appstore
Did you use the correct version? Since today there is a new version for Mx7
I tried the Drop Zone widget for version 7.0.2, I am able to upload images but it is not getting saved properly.I have added the microflow to commit image object in the 'ON Change event'. PFA of the screenshot of my application.
JAM-IT will release a new Multiple Upload widget soon. So keep watching the Appstore :)