Whether I make or take a call using my Android smartphone, I cannot end the call by selecting the "End Call" button. It is still blue and not the selectable red color. I have to back out of the app, pull down the settings screen on the phone for active apps, reselect the app, and hope that the End Call button is now red and selectable. If not, I have to repeat or stay quiet until the caller disconnects the line. Even then I have little assurance that the call is truly disconnected. Additionally, after I hit call, none of the features like "hold," "mute," "audio source," or "dialer" are selectable. So if I accidentally call the wrong number, I can't hang up quickly. I'm stuck even if the caller answers. Is this an app incompatibility issue or something else? Any solutions?