From the iOS & iPadOS 16 Beta 3 Release Notes: Conditional views in columns of NavigationSplitView fail to update on some state changes. (91311311) Workaround: Wrap the contents of the column in a ZStack. It mentions NavigationSplitView, but it must apply to NavigationStack as wrapping the if statement in your example in a ZStack updates the view.
Topic:
UI Frameworks
SubTopic:
SwiftUI
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