A few minutes ago, another player asked me where to get battle sprite harnesses. I told them to go to the Laboratory, which they did, and they told me there wasn't anyone to buy the harnesses from in there. I went to check it out, and sure enough, Riley is gone.

The changes to the Lab are cool, but it seems that, at some point, Riley got removed, and nobody remembered to put him back in. I've checked the rest of the Lab, and the Hall of Heroes and the Bazaar just in case he somehow ended up there, but he seems to be gone entirely.

In case it helps, I've finished all the rank missions, while the player I was helping hasn't started the rank 6 missions yet, so Riley is missing from at least 2 different iterations of the Laboratory.