I don't think McAfee are marking attacks as recommended for blocking any more. I'm sure I read a KB article on this earlier in the year.
Are the attacks that show RfSB = Yes all old attacks? Is this only occurring on a manager after upgrading to 8.x?
This is the article I was referring to
Network Security Platform Recommended For Blocking (RFB) Attack List (no longer updated/maintained)
Technical Articles ID: KB55451