Transfer Shapekeys (to cloth) -> not all shapekeys are listed. I miss "Ultimate Natural" shapekeys

For fitting the cloth I use “Tranfer Shapekeys”, but I can’t find all custom shapekeys in the apearing list. I miss the “Ultimate Natural” keys for example. So I can’t fit the cloth exactly to the body. Wht is the criteria for listing the keys? Or is there an other way to transfer this shapekeys to the cloth? (shrinkwrap is not the perfect solution)