Well, so far its only happened with Sydney (for me) - quite frequently, I might add.

With regards to the other problem where the morphing brush seems to stop working, this is more when I am in Combine mode, and I've locked some of the face-shaping morphs (but not others). 

For example, I have one of the DAZ figures opened, and I have loaded up all of the head morphs. I then select the morph tool, and click the Combine tab. The list of morphs appears. I figure that if I only want to re-shape the nose I should lock everything else except the nose morphs. At this point, it stops working (it seems to not work if I flick back into the Create mode as well).