SU 27 radar problem?

Lately I’ve been playing with the su 27, and I’m having a serious problem. first of all I find it useless when using Radar/IRST beyond/within visual range combat that the reticle is extremely short towards the bottom and excessively long at the top as I go outside of the visual range, and secondly often when I have enemies higher up than me, with a full blue background of the sky behind, the radar in SRC PD mode even from close ranges under 10km, and with the plane arriving head-on it is unable to lock onto it. paradoxically the mig 23 has a better and faster radar lock. anyone have the same problem?