PropertyInfo.GetCustomAttributes never returns attributes inherited from the base class if the property is an override.
Even worse, if you ask for Attributes.IsDefined with the same values, you will get a true!! :S:S:S… Can’t believe a release of .NET comes out without an automated test for those kinds of things…
You can see the bug, get a repro class, and vote for it on Product Feedback.
/kzu