Inheritance in SwiftData — Fatal error: Never access a full future backing data

I'm implementing SwiftData with inheritance in an app.

I have an Entity class with a property name. This class is inherited by two other classes: Store and Person. The Entity model has a one-to-many relationship with a Transaction class.

I can list all my Entity models in a List with a @Query annotation without a problem. However, then I try to access the name property of an Entity from a Transaction relationship, the app crashes with the following error:

Thread 1: Fatal error: Never access a full future backing data - PersistentIdentifier(id: SwiftData.PersistentIdentifier.ID(backing: SwiftData.PersistentIdentifier.PersistentIdentifierBacking.managedObjectID(0x96530ce28d41eb63 <x-coredata://DABFF7BB-C412-474E-AD50-A1F30AC6DBE9/Person/p4>))) with Optional(F07E7E23-F8F0-4CC0-B282-270B5EDDC7F3)

From my attempts to fix the issue, I noticed that:

• The crash seems related to the relationships with classes that has inherit from another class, since it only happens there.
• When I create new data, I can usually access it without any problem. The crash mostly happens after reloading the app.

This error has been mentioned on the forum (for example here), but in a context not related with inheritance.

You can find the full code here.

For reference, my models looks like this:

@Model
class Transaction {
	@Attribute(.unique)
	var id: String
	var name: String
	var date: Date
	var amount: Double
	var entity: Entity?
	var store: Store? { entity as? Store }
	var person: Person? { entity as? Person }
	
	init(
		id: String = UUID().uuidString,
		name: String,
		amount: Double,
		date: Date = .now,
		entity: Entity? = nil,
	) {
		self.id = id
		self.name = name
		self.amount = amount
		self.date = date
		self.entity = entity
	}
}

@Model
class Entity: Identifiable {
	@Attribute(.preserveValueOnDeletion)
	var name: String
	var lastUsedAt: Date
	@Relationship(deleteRule: .cascade, inverse: \Transaction.entity)
	var operations: [Transaction]
	
	init(
		name: String,
		lastUsedAt: Date = .now,
		operations: [Transaction] = [],
	) {
		self.name = name
		self.lastUsedAt = lastUsedAt
		self.operations = operations
	}
}

@available(iOS 26, *)
@Model
class Store: Entity {
	@Attribute(.unique) var id: String
	var locations: [Location]
	
	init(
		id: String = UUID().uuidString,
		name: String,
		lastUsedAt: Date = .now,
		locations: [Location] = [],
		operations: [Transaction] = []
	) {
		self.locations = locations
		self.id = id
		super.init(name: name, lastUsedAt: lastUsedAt, operations: operations)
	}
}

In order to reproduce the error:

1. Run the app in the simulator.
2. Click the + button to create a new transaction.
3. Relaunch the app, then click on any transaction.

The app crashes when it tries to read te name property while building the details view.