Sorry for the late reply and thank you for reporting the issue. Drag and drop feature is not available in mobile devices yet. Our devs are working on it however you should be able to add /edit & delete task. You will see the edit dialog on clicking the task. May I know which android device you are using and the version of android please. May I ask for the screenshot or video recording of the issue if possible.
We appreciate your patience.
Customer support service by UserEcho