In my 2013 new Komfort 29' TT I fill the tank slowly, just as my manual requires. Even so, there is no escaping air noise from the vent until about half way full and then there sounds a sort of "release" and sometimes a bit of water spurt. Thereafter you can hear the gurgling of the vent normally heard during fill, and the tank takes on gently about the other half's worth.
It seems apparent there is some sort of material causing a plugged condition. Probably an assembly "quality" issue. But after at least 20-25 fills it still does it. Every time I take my problem to the better of the two "dealer" Dutchmen repair shops they act like they aren't happy to see me. That probably comes from one of my original manufacturer warranty/satisfaction claims regarding misaligned and crooked cabinet door hardware. Another poor quality installation where holes were drilled cock-eyed. So I don't got to the dealer anymore. Their attitude wore me down.