I've searched through but haven't seen this one before. I had two games going side by side - both at approximately the same place. I had converted all the blue masks on both games, and had all the purple except the science master. On the first game I got a spontaneous conversion of the MOS so he didn't drop his piece of necklace - so I had to start again.
On the second game I converted the MOS in the normal way but he still didn't drop a piece of necklace - so now what do I do. I am running on MacOS 10.6.6 and I'm wondering if the glitch is OS related. My daughter hasn't upgraded her system and had no problem. Grrr!