Crossover521

I noticed the same issue and I was wondering whether I'm just not configuring the AP properly though in my case it seems to trim down and the aircraft dives. I adjust my selected attitude and then hit the ALT button and as soon as I engage AP it starts diving. It happened on every flight so I simply stopped using altitude hold. A basic bypass is to level the aircraft at your desired altitude and then engage the AP. It will maintain your attitude at the time of engagement so if you're level it will remain there.