Recently I found that emails hitting one of the Incoming Mail Policies seemed to only be checking on the first (p1) priority and ignore the second (p2) if first one is not met.
I have Mail Policy Settings Match Priority set as: P1 Envelope Sender P2 Header "From"
The Incoming Mail Policy is at the top. Any sender added is only considered matching based on envelop sender. If an email is coming that should be matching based on header from it is not being considered and keeps going down the Inc. Mail Policy list.