System.InvalidOperationException: Late bound operations cannot be performed on types or methods for which ContainsGenericParameters is true

Seems the generated proxy has problems with methods with generic constraints:

[exec] System.InvalidOperationException: Late bound operations cannot be performed on types or methods for which ContainsGenericParameters is true.
[exec] at System.Reflection.RuntimeMethodInfo.ThrowNoInvokeException()
[exec] at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture, Boole
an skipVisibilityChecks)
[exec] at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
[exec] at NHibernate.Proxy.DefaultLazyInitializer.Intercept(InvocationInfo info)
[exec]
[exec] Unhandled Exception: System.ServiceModel.FaultException`1[Orbis.OA.Common.WcfService.ContractBase.Faults.InternalSystemFault]: System.InvalidOperati
onException: Late bound operations cannot be performed on types or methods for which ContainsGenericParameters is true.
[exec] at ContactProfileProxy.ValidateProperty[T0](PropertyInfo )
...

This is the signature of the method in InternalEntityBase

public virtual ErrorList ValidateProperty<T>(PropertyInfo prop) where T: InternalEntityBase, IPersistable