Password/SMS verification AutoFill not working on iOS TextInput

Apple has a possibility to auto fill all text inputs: Enabling Password AutoFill on a Text Input View. Most of the cases it should work out of the box, with an optional input field tagging that should make it more reliable. I tried to use "one time code" autofill (SMS verification code) but it doesn't work out of the box.

So I tried to tag the input field with a patch to

qtbase\src\plugins\platforms\ios\qiostextresponder.mm

By adding the following tagging into "initWithInputContext"

if (@available(iOS 12, *)){
   self.textContentType = UITextContentTypeOneTimeCode;
}

But that didn't help either. Just in case I commented out all the other configurations in this function, to make sure that something else doesn't forbid it. But still no luck.

Does anybody have an idea what could forbid iOS to open the keyboard suggestion "From messages" when correctly recognized verification code comes in with SMS? I'm willing to try an test but I'm out of ideas.