The PTT button on Android won't stay pressed.
Try pressing and holding any context menu, if after a few seconds it activates the menu the problem is your phone. That's because some phones report your touch has been released when it has not. One work-around is assigning a PTT hardware button. The only other work-around is change the talk button action to Toggle (in Options>Push-to-talk button).
Questions? Submit a new ticket for support-related inquiries.