When the Improv button is clicked and music starts to play, autoscroll does not always work. I found that if the "play" and "pause" buttons get pressed before and then "improv" gets pressed (without clicking on the sheet in between the other clicks), autoscroll works normally. However, if the "improv" button gets pressed before anything else in the program, autoscroll doesn't work.
I ran Impo-visor on Windows 10 x64 and JDK 8 Update 102.
Fixed in forthcoming version 10.
Fixed in forthcoming version 10.