no answer so far...
i did some more testing and realized something even more strange!
i built a quick profile on everyday glossy.. same limit in yellow..
i printed with the semi prem settings on my proofing paper.. same limitation
i used the settig "hp semi proofing".. and printed on the semi prem paper.. et voila.. i get the same gamut then with the setting semi prem + the yellow!!.. ??
now.. how can that happen