sometimes it happens that the position of the arrows, of a single round, in the app is completely lower or higher compared to the position on the target.
What can be the reason?
This is a clear indication that the calibration is lost. Possible reasons are:
RyngDyng lost its position, maybe it sank down on soft ground, such as grass
The target has moved. Maybe arrows hitting the target pushed it backwards
The target surface is very uneven. Best accuracy is achieved when the surface is flat and the chessboard is fixed tightly to the target when doing the calibration. Then tightly fix the target face to the target surface using enough pins.
When you experience such a loss of accuracy, repeat the chessborad calibration. Alternativly, you can try to bring back target and RynghDyng to its original position; but this is practically possible only when the original positions have been marked on the ground.