Core Data Inheritance entities not being saved - swift

Question

I have the following Data Model in Core Data:
*Note: I Setup Attachment to be Abstract and ExpenseAttachment and LeaveAttachment have their parent set as Attachment
When I try to save ExpenseAttachment or LeaveAttachment, I run intro the problem that the code to save a new attachment runs fine with no errors, but nothing really happens, since when I try to retrieve it there are no records.
So I use this code so save:
func syncExpenseAttachments(attachmentResponse: AttachmentResponse, expenseID: Int64)
{
let backgroundContext : NSManagedObjectContext! = DataController.sharedInstance().backgroundContext
backgroundContext.perform
{
let attachmentExpense = try? backgroundContext.fetch(Expense.fetchRequest()).filter { $0.tkID == expenseID }
let attachment = ExpenseAttachment(context: backgroundContext)
attachment.tkID = Int64(attachmentResponse.id ?? 0)
attachment.createdDate = attachmentResponse.createdDate ?? Date()
attachment.name = attachmentResponse.name ?? ""
attachment.flaggedForDelete = false
attachment.data = attachmentResponse.data as Data? ?? nil
if let attachmentExpense = attachmentExpense {
attachment.expense = attachmentExpense[0]
}
try? backgroundContext.save()
}
}
And this code to get the records:
let attachmentRequest = NSFetchRequest<NSFetchRequestResult>(entityName: "ExpenseAttachment")
let sortDescriptor = NSSortDescriptor(key: "name", ascending: false)
attachmentRequest.sortDescriptors = [sortDescriptor]
do {
let coreDataExpenseAttachments = try DataController.sharedInstance().viewContext.fetch(attachmentRequest) as! [ExpenseAttachment]
//Do some work
} catch {
print(error.localizedDescription)
}
After the save, trying to retrieve attachments returns nothing. However if I simply use the Attachment entity with saving, I can actually see records when I also try to retrieve data for the attachments enitity. I though you do not create or save the Abstract Parent Entity, just the Child Entities?