I have recently collected all colors of wool in a minecraft world eligible for achievements while logged in and have noticed that the count does not increase when I collect wool of a new color, nor did it complete when I collected all the colors.  I created new worlds and tested it in those, but the count will not increase.  On a related note, I also tried the achievement "It's a Sign" to test whether achievements seemed to be working, and that did not either.  I am unsure as to whether achievements as a whole are not progressing or just those two.  I have two wool marked down on the Rainbow Collection achievement, but it is not progressing past that.