It's difficult to provide a precise explanation, but in SwiftUI, it's best to follow these two principles: Avoid changing a view's open/close state simultaneously with other states. Adding a slight delay can help avoid many issues. Avoid animating states that don't need to be animated.

func query(group: Group) { let id = group.id let predicate = #Predicate<Item> { item in item.group?.id == id // Compiles } } @MarcusAurelius This method can indeed compile, but when I use similar code to run, the following error message will appear: Thread 1: Fatal error: Couldn't find \Tag.id on Tag with fields May I ask if your code can use the above predicate to fetch data?