It seems that you are facing the same issue in this thread(http://community.powerbi.com/t5/Developer/Tweaking-an-existing-Custom-Visual-the-change-is-successful-but/m-p/107019#M3739).
It seems that you are facing the same issue in this thread(http://community.powerbi.com/t5/Developer/Tweaking-an-existing-Custom-Visual-the-change-is-successful-but/m-p/107019#M3739).