Mass Effect 2 Bug * no spoilers *

Ok for those of you who have the game.
When you are doing the 'loyalty quests' Make sure you save a lot.
There is a bug that may cause the 'loyalty power' not to unlock.

I went through this with Grunt. Had to start the whole quest over again.
According to some forums it appears to be random. Happens most of the time with Grunt, Samarra and Thane mostly.