Probably, the elements aren’t defined as accessibility elements. Note that it is not that easy to make them accessible 
Personally, I had issues with it as well, maybe there will be another developer here who’ll bring a bit more light on the subject and how to do it correctly…
But, if I remember correctly, UIKit elements are accessible by default, custom views can become a problem. You need to make each container view isAccessibilityElement = false and for its children set isAccessibilityElement = true
In the meanwhile, you can try to read this: https://developer.apple.com/documentation/accessibility
and this: https://developer.apple.com/documentation/uikit/accessibility_for_uikit