Blocked Emails Going to Flagged Folder

Why are spam emails that I have blocked, and yes I see the block symbol and Apple Mail even says, "This is from a blocked sender.", going to my "Flagged" folder? I've finally accepted that Apple doesn't really care and they will continue to clog my "Junk" folder even with filtering turned on, but this is too much. I mean, what's the point of blocking if you're going to allow them through anyway? Anyone have any tricks or advice how to get rid of known spammers? Thanks