kackojan

Hi, i am using iFly for quite some time now and lately i have this quite big problem. When I fly normal flight and I set up everything proper, the whole flight is okay, takeoff, climb, cruise and even descend is fine, but.... before end of descend (in order to meet STAR restictions) i control my descend by A/P speed and altitude in MCP. This is still okay. Normally i use alt 3000ft or 2500ft (alt is locked and holding), and speed around 200-210kts with flaps 15 when i fly intercept course before IF and here comes the problem... When plane starts to turn to final the altitude sinks a bit (which is normal due to less lift on wings during turn) but then the alt hold quits working and plane starts to sink rapidly. The only thing to do is to manually fly the aircraft to landing... I cannot even reset the A/P (i disengage it and set up again but altitude still doesnt work), only heading and speed is working. In good visibility conditions it is not so tragic but when it is foggy it is nightmare... And then when i want to do the same descend and approach part again to see if it happens again, everythig works normal... I just set up plane before final point of STAR set everything up like in normal flight and do exaclty the same procedures like in full flight and nothing happens.. I turn to final, establish on LOC and G/S and land even in dual A/P mode without any problem... I don't get it at all...