title: ambiguous for type lookup in this context when -com.apple.CoreData.ConcurrencyDebug 1 is active
body: <p>The code below runs perfectly fine when I have the above parameter turned off in my Scheme.  When it is turned on I get a 'Group' is ambiguous for type lookup in this context crash error. on the line &quot;let currentGroup = context.object(with: groupID) as? Group&quot;</p>
  <p>I've checked my project and there is no duplicate reference to Group NSManagedObject.</p>
  <pre><code>let context = CoreDataStack.shared.newPrivateContext()
      if reset {
          AppDefault.current_ListGroup = nil
      }
      if let groupID = AppDefault.current_ListGroup,
           let currentGroup = context.object(with: groupID) as? Group {
          return currentGroup.objectID
      } else {
  </code></pre>
  <p>Can someone help me figure out why it works with the .ConcurrencyDebug 1 off but crashes when it is on?</p>
  <p>Thanks in Advance</p>