If you valued a business interest (such as a FLP) that owned Madoff securities ON A VALUATION DATE BEFORE THE FRAUD WAS DISCOVERED, should you now revise your opinion?
Going back, once again, to Revenue Ruling 59-60, Section 3. Paragraph 3, valuations are based on facts available as of the valuation date. The fraud was not known as of then. Therefore, from an (admittedly narrow) APPRAISAL point of view, I do not think you should revise your opinion.
From a LEGAL point of view, there may well be grounds that allow for a revision, but I am not an attorney, am not equipped to address those issues, and I will not.