Skype IP Exception

I'm blocking Skype using the IM/P2P classifier with my HTTP Proxy (standard)

I've validated that Skype works when I turn off blocking.

However if I make an exception for a certain IP and check Skype, it does not work.

Putting that IP in the Classifier Exclusion under Advanced also does not work.

The only thing that works is to turn off Skype blocking entirely.

What am I missing?

Thanks.

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