Hi Chad,
I haven’t seen anything similar, though the ScreenReader isn’t used too widely so we may have just not run into it yet. Are you only seeing this in development builds? That does look like the proper, top-level window, so perhaps a good first step would be to add some additional logging to FSlateAccessibleMessageHandler::GetAccessibleWindow and FSlateAccessibleWidgetCache::GetAccessibleWidgetChecked to see why it’s returning null. It looks like either the SWindow is not valid, not accessible, or the accessibility system isn’t active yet. Knowing which of those conditions is failing should help narrow down where the problem is, I wonder if it’s some race condition where a Windows message sent very early is being processed before the accessibility system is initialized.
Best,
Cody