Beechcraft Baron PA58 no ALT in G1000

In the Beechcraft Baron PA58 I find no ALT button (bottom left) in the G1000 to adapt the height. How does it work?

Welcome. It’s a bug. It has been reported. Right now all you really can do is use vertical speed and watch your altitude. Hit Alt Hold when you get to your desired altitude.

You could always assign buttons to increase/decrease altitude via controls menu until fixed.