Belt dressing should not of been used. I have had this happen on many vehicles that I have replaced the belt. After checking pulleys for running true, I have found sometimes, but not always, a fine piece of debris like paint, undercoat, glue to name a few on the inner edge of one of pulleys or a weak belt tensioner. Some times taking the serpentine belt off and reinstalling the belt in the opposite order of the way it previously rotated took care of the problem. Also check the new belt for a rough edge.
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