For a while, after the introduction of the Revolution, you could not look up any artist who had a punctuation mark in their name. You would get that message saying the artist did not exist. I thought it had been fixed, and I have not had any problem with it for quite a while. Sounds like you have run into something similar. The way things appear and disappear around here, I'm not surprised.

"If your pictures aren't good enough, you're not close enough."  ...  Robert Capa