iOS: Focussed text-field freezes parent window

Closing a window with a search being in focus, the parent window freezes. We haven't been able to provide an isolated test case, but it can be reproduced with a list-view + search-bar. I suspect the search-controller does not hide before the parent window closes and then stays in the VC stack.

I don't see any possible workaround so far, except overriding the native back button with an own one which is a no go as well.