Why do you always need to factory reset the LP2 pen, before reconnecting to the same or other phone? Is it a bug?
In case the pen was already paired and has got a connection link it will try to connect the paired device when "Send" pidget is ticked.
To make the pen discoverable "Pair phone" pidget should be used.
"Send" pidget initiates "Discoverable" state of the pen only when there is no link key in pen (after factory reset, or for never paired pen). "Send" pidget is trying to establish connection between pen and device pen was paired to and send data to this device. Since pen was removed from paired devices on phone the connection will not be established and consequent error buzzes with re-connection attempts will occur.