Like title say, the third perk of the skilltree "Steward" which quadruples the prosperity growth rate of the settlement in which you are waiting, does not work. I tried it out in my poorest settlement, to give it a boost and watched the prosperity. It's expected change befor me waiting there was +1 because of loyalty and the stat was at 865. After waiting there for a whole day, the prosperity changed by 1 point to 866.