On DMM, I used my black ticket to get Grace.

First 7 Rainbows I fed her resulted in 4/5... but I've since fed he, and I kid you not, 47 more rainbows and still not gotten that last skill up.

It's really disheartening, and I'm curious if there is some sort of bug going on or something else, or if I'm due to be struck dead by a meteorite when I step outside.