Xbox Controller Can't Bind A + Up(dpad) or A + Down(dpad) to function

Xbox Elite Series 2 controller. I’m not using default controls and I already deleted all default assignments completely and started my own from scratch before I started this thread. I don’t like the default controls and wanted to make my own. This isn’t about the “increase flaps” bind. This bug occurs whether I try to bind “increase flaps” or something else like “toggle ifr view” to A + Up(dpad) or A + down (dpad).

I’m glad you have noticed that some combination binds don’t register. It’s odd that A + Up or Down (dpad) doesn’t work but B + Up or Down (dpad) does.