I've been stuck for 2 days on the second part of Buzz's quest where you need to find 15 aliens. Found 8 the first day, and was at 14- 2 days ago I have been backtracking and going into every house multiple times to make sure. Today I went into Merlin's house and it was underneath a pile of books. I only noticed it because of it's shimmer. But you had to be very close to it.

I had someone else that I know was also stuck at the same point and they also went into Merlin's house and their alien was in the bookcase underneath it, they had to interact with a bookcase to get it. Once again, they were able to see a slight shimmer effect when they were up against the bookcase but couldn't see the physical alien toy.