After flying the King Air C90 for a while in autopilot the response to changes in altitude is erratic, and at the same time the altitude indicator and VSI are stuck, even when disengaging the autopilot.To some extent this can be corrected by forcing a reload of the aircraft, but you don't want to do that all the time, as it messes up some of the settings. Sometimes the situation corrects itself and the altitude dial starts spinning to the correct altitude and all is OK, but by that time it is some 10 minutes later. Sometimes flying at a fixed altitude the plane slowly starts loosing height. It started after downloading X-plane 11.01 a few days ago, which changed the look of the cockpi panel of the C90.