WLP007 does compact pretty well, but it has never completely plugged itself in the cone for me. Try adding a little headspace pressure (1-1.5 psi) when you dump. This will help push the yeast/trub out the valve and prevent any possibly of a vacuum forming in the headspace during the process. Having a bit of headspace pressure will also prevent any oxidation that would result from air being sucked in through a airlock or the dump port itself. These fermenters are not designed to hold much pressure, so keep the pressures below 1.5 psi. What steps are you taking to leave the majority of solids in the boil kettle and out of the fermenter during transfers?The amber ale I made has WLP007 in it right now as a matter of fact. Ive tried dumping it every day since fermentation started on this batch. It's been coming out like a thick sludge once I can get it moving with shooting co2 up inside the dump valve to break it loose. It's more trub than yeast, very little whiteness of the WLP007 in it.