There are rebar handles with invalid selected targets to constrain. The bar preview corresponds to latest valid constraints.

public static FailureDefinitionId CannotSolveRebarWithDelayedConstraints { get; }

Public Shared ReadOnly Property CannotSolveRebarWithDelayedConstraints As FailureDefinitionId
	Get

public:
static property FailureDefinitionId^ CannotSolveRebarWithDelayedConstraints {
	FailureDefinitionId^ get ();
}