On android, very often the application does not respond. This happen both when I want to start a time tracking or stop a running one. Observed 30% of time during one month evaluation. I overcome the problem by killing the application and relaunch it. Fortunately I do not loose any data. But the time loss is too much. It seem to me that there may be is a correlation with internet connection loss because it happen more when I do move. Tried on Huawey tablet, Wiko phone and Oukitel phone using Timecamp android app v2.3.3.