Seemingly Odd Behavior ?

Hello all,

I think Im  experiencing an odd behavior by ASP4,  P3D V4.5 HT3, I also have REXSF but I dont think it's related 

The pop up weather systems!! It happens in my case on two levels -always using real weather mode- 

1- I am flying with clouds around and suddenly in a range of 5-20nm or more a large cloud forming in front of my eyes in less than a second or so?

2- At cruise altitude the weather radar is on and not showing any significant weather systems for 40 or 60nm ahead I look away or check regularly every few minutes to see with a surprise a huge system right in the middle of the screen it must've popped up because if it didnt I should of seen it coming?

Both are slightly annoying specially the second one because mostly the systems had a red cell and should be avoided, for at least two advanced models of aircraft I'm flying regularly I have to check the flight path all the time or the autopilot will get disconnected then the aircraft would go into a steep dive and mostly crash or lose significan altitude?

Any ideas will be appreciated please

Best regards

Alaa Riad