How to get the keyboard to work with Voice Over on iOS?

The touchkeyboard on iOS doesn't function as expected when Voice Over is turned on.

If you have Voice Over turned on, the keyboard normally/natively (at least sind iOS 10) works that way, that...

• each button on the keyboard has a black outline you can navigate through the buttons by swiping left or right

• each button that comes into focus is then spoken bei Voice Over

• you double-tap, if you want to enter a character (type the letter)

With Unity, the iOS touchkeyboard & Voice Over turned on doesn't show the black outlines and doesn't allow the user to swipe left an right to navigate through the buttons. Instead if you tap on a button it is spoken via Voice Over and immediatelly typed. For blind and visually impaired people this is really a problem, they are not able to use this keyboard.

Does anybody know a way, how change this? Is there any way to get the normal/native iOS keyboard (since at least iOS 10) to work?

I've tried changing the deployment target, but this doesn't change anything.

Any suggestions? Work arounds?

Any help is appreciated!