Wind Angle vs. Direction: If you are displaying Wind Direction then wherever the arrow is pointing is what you see on screen. But if you are displaying Wind Angle, that is relative to the boat’s heading. To avoid the need to buy compass hardware to mount on the boat, we use your GPS heading to derive wind angle. So if the boat is not moving, Wind Angle should not be displayed.
The Limits of GPS Accuracy for True Wind: When you are not moving, it is always best to use Apparent Wind Direction and Speed, not True. But sometimes even then you may notice that a navigation app reports that you have a boat speed of 1-3 knots, as the GPS tries to detect your position. That phantom movement enters the calculations for True Wind Direction and Speed, making them unreliable when not moving. The problem is that GPS is only accurate to within say 40 feet (13 meters) on the face of the earth. That means there is a circle around your location with a diameter of 80 feet (26 meters), within which GPS technology is not accurate enough to know if you are moving. If the GPS speed and heading jump around, it causes True Wind Direction and Speed to jump around too.
This does not happen with True when you are moving in your boat; it only happens when you are standing in one place. Use Apparent Wind Direction and Speed when at the dock or at anchor, and you should have no problem.