The plane does not see the radar or the mark in the game, cheating or bug ?

[Venom]

Can someone explain to me how it is possible that I absolutely do not see some enemies on the radar, whether I call HDM PD, SRC, or other modes, I fly low, high and even the game does not see them, which does not mark them in ARB, and I notice that there are 3- 4 kilometers. And there was no hill or horizon behind which they would be hidden from radar, etc. The game even marked the plane for me when it was one kilometer from the front door. Is this some new kind of cheating or some bug in the game?

[Wandering Flare]

That's just radars in WT. Even under perfect conditions for the radar to spot something it might fail spectacularly.