iOS Keyboard & Voice Over Problem

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.

@Unity is there any possibility to change this? 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?