Some user experience a situation where their tactical map appears to be quivering, jumping slightly vertically or horizontally. In addition, they may find the map zoom (pinching or spreading two fingers on the map) does not consistently perform the action they want. This is normally caused by the device being in the “Track Up” map action setting.
In the “Track Up” setting, the device is attempting to “track” the unit itself and adjust the map around it. When in motion, the unit will always point to the top of the map, and the map will rotate around it, keeping the “track” of the vehicle always facing the top of the map. When the unit is stopped, slight variations in the data provided by the device’s GPS chip may cause the map to re-center or rotate ever so slightly in adjustment to these GPS readings. This can give the appearance of a “jittery” map. Likewise, if you zoom the map to a location that does not include the unit itself, the “Track Up” feature will attempt to automatically re-center the map to include the unit. After all, this mode is supposed to “track” the movement of the vehicle. So, this is normal.
In order to return the map to normal behavior, put the map in “North Up” whenever you are not specifically desiring to track your vehicle during movement.