To the user that claimed that the app is incorrect:

Im a flight instructor and can confirm that the app works correctly.
The visualizer is mirrored to the map plan view since your point a view when looking at the DG is different then your point of view when looking at a top down map view. The tutorial in the app explains this.
You can verify this by comparing the results from the plan view and from the visualize mode are see that they are in fact the same.

CFIpilot12345 about Holding Pattern Trainer