@elglon So I tried again today, and it worked just fine for me! Flew a beautiful flight from Mount Cook to Queenstown. Bumpy approach in the mountains, but not bad for my first try.
I have some competing theories regarding what was going on. Firstly, I turned off all engine failures (though none were registered). I did not have any open circuit fuses. Secondly, I closed the app SkyDolly, which I use for inflight recordings. I've noticed previously that SkyDolly has done some strange stuff to my airplane systems. I'll see if I can reproduce the issue and post back any updates that I have. But for now, the issue seems to have been resolved.