List rows disappearing when scrolling

I have a List containing ItemRow views based on an ItemDetails object. The content is provided by a model which pulls it from Core Data.

When I scroll through the list one or two of the rows will disappear and reappear when I scroll back up. I have a feeling it's because the state is being lost?

Here's some relevant info (only necessary parts of the files are provided):

-- ModelData.swift:
@Observable
class ModelData {
	var allItems: [ItemDetails] = coreData.getAllItems()
	...
}


-- ItemDetails.swift:
struct ItemDetails: Identifiable, Hashable, Equatable {
	public let id: UUID = UUID()
	public var itemId: String  // Also unique, but used for a different reason
	...
}


-- MainApp.swift:
let modelData: ModelData = ModelData()  // Created as a global

class SceneDelegate: UIResponder, UIWindowSceneDelegate {
	// Methods in here (and in lots of other places) use `modelData`, which is why it's a global
}

@main
struct MainApp: App {
	var body: some Scene {
		WindowGroup {
			MainView()
		}
	}
	...
}


-- MainView.swift:

struct MainView: View {
	var body: some View {
		List {
			ForEach(modelData.allItems, id: \.id) { item in
				ItemRow(item)
			}
		}
	}
}


struct ItemRow: View, Equatable {
	var item: ItemDetails
	var body: some View {
		...
	}
	static func == (lhs: Self, rhs: Self) -> Bool {
		lhs.item == rhs.item
	}
}

There's obviously more code in the app than that, but it's not relevant to the issue.

I've tried:

• ItemRow(item).equatable()
• Wrapping ItemRow in an EquatableView
• Giving the List a unique id
• Using class ModelData: ObservableObject and @StateObject for modelData

None made any difference.

I'm using iOS/iPadOS 26.0.1, and I see it on my physical iPhone 17 Pro Max and iPad Pro 11-inch M4, but I don't see it in the equivalent simulators on those versions. The Simulator also doesn't exhibit this for versions 17.5 and 18.5, and I have no physical devices on 17.5/18.5 to check.

Should I be doing as I currently am, where I create modelData as a global let so I can access it everywhere, or should I pass it through the view hierarchy as an Environment variable, like @Environment(ModelData.self) var modelData: ModelData? Bear in mind that some functions are outside of the view hierarchy and cannot access modelData if I do this. Various things like controllers that need access to values in modelData cannot get to it.

Any ideas? Thanks.