xcode 4 crash at marking references inverse

For the third time in a row, I create a blank navig开发者_如何学Goation-based iOS project, create two entities in the core data model, create references from entities to one another, and the second I mark them as inverse, this happens:

UNCAUGHT EXCEPTION (NSInternalInconsistencyException): Cannot remove an observer <IDEDMArrayController 0x27fbcc0> for the key path "inspectedInverseRelationship.name" from <CDMRelationship 0x2911060>, most likely because the value for the key "inspectedInverseRelationship" has changed without an appropriate KVO notification being sent. Check the KVO-compliance of the CDMRelationship class.

What can I do to avoid it?