Just trying this again now and still not working, always wants to fly north initially
I was able to change the heading as suggested using the “set heading bug” (Ctrl+Ins / Ctrl+Del keybinds respectively) commands and confirmed it was changing using the PMS50 addon
My guess is Asobo never thought to update the desired heading for the GTN530 and it’s intended to simply be used as a pilot guide when flying by hand. Moving the “desired heading” knob is not represented in the popup GTN750 autopilot, unlike when pressing the keybinds.
I reloaded the classic version to confirm and the “desired heading” on the classic compass is not the same as on the one above the radio compass. Changing the classic desired heading knob is updated in the PMS50 popup as confirmation.