I've seen this problem before with genuine Ducati filters, where the rolled steel rim is too tall to let the seal compress properly. Or maybe the rubber is not thick enough? Either way there is a height deficit!
This is a historical fault and I would have though that all the faulty ones were long gone, but clearly some still keep surfacing!
I use K&N with no problems, barring the hexagon coming adrift occasionally when I try to remove the filter with a spanner.. No problem really as I just whack a screwdriver through it.
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