Std Pressure

When I am climbing past the TA and press STD on the EFIS, STD appears on the PFD under the altitude ribbon but the change to standard pressure is not sent to the autopilot. The altitude is still based on the pressure at takeoff which could be very different. The result is that I am at the wrong altitude and ATC gets very angry. I have to manually change the pressure setting back to 1013 which I should not have to do. If I click on the STD button on the PMDG 2D EFIS panel the altitude displayed quickly changes to reflect the change back to 1013 hPa pressure. This is what happens on a real aircraft but does not happen using the hardware.