Engine braking not working correctly

[Rake12]

My engine braking is not working properly. Let off the gas it works great but then it free wheels for about 3 or so seconds then grabs again. It is a new belt and clutches are clean one thin shim in secondary but belt does squeal but only when first starting bike and belt is cold, ok after 1 min of driving. I realize that that belt is not getting grabbed by the clutches properly so will take it apart when I get home. Any other thoughts on this?.