I asked for this capability a few months back and DD says its my device. It works fine on Apple apparently but only on some Android and Windows computers (but not mine). DD tests on Android and Windows and do not see what you and I are seeing. I gave up asking and just put up with the failing. DD did offer to do a live session with me to sort this out but I got too busy with my programming efforts to process DD 3D model in Rhino. Maybe this is something you have time to pursue with DD and finally get to a conclusion. It would be a nice if the DD App would support smooth scrolling for our devices.
What the DD App does is follow the increments set by the +/- buttons when you scroll. Since the +/- buttons are too coarse to adjust the map to be reasonably close to the screen boundary, you end up being frustratingly too small or bigger than the screen. There is nothing in between. But this problem does not exist when viewing the 3D model so it is not a case of our devices not being able to interface with the DD App. It is the case that the DD App does not work with our devices when viewing the 2D maps (ortho, Plant Health, Elevation).
Maybe DD could just put finer steps into the +/- keys and then our scrolling would work better.