The user interface for choosing the second app is so bad it’s almost incomprehensible. It’s like no one in Apple ever tested it. As soon as you open the special app picker for the second app, you get a scrolling list of apps that support split view.
Except it’s in no discernible order, whether alphabetical or where it’s installed on the iPad or anything. And there’s no search so you can just type in the name of the app you want. No, you have to scroll and scroll and scroll, looking for the app, hoping you don’t blink as it goes by. I think this could only be worse if the picker scrolled itself at high speed and you had to tap on the app as it went by.
Apple is supposed to be the “every little detail” company, but once in a while you get glitches like this and wonder how it got through.