Quote Originally Posted by Hulan View Post
If the server only updated the clients on the position of monsters within a 50 yalm range (about the range that monsters start loading on the screen anyway), that would drastically impact 3rd party apps' abilities to track monster movement at long range.
This is exactly how it works now. The server only tells your client about entities in your area of interest, which is a bubble centered on your character with a radius of about 50-60 yalms. Radar apps cannot detect marks outside of this bubble because the client simply does not know about them.

As a few others have mentioned, there is basically nothing they can do to stop the radar apps from a technical standpoint. Something will need to change in the way the Hunt system is designed if they want to mitigate the impact of these kinds of programs.