Okay, Blogger has decided to be "helpful" and change something again. Whatever it was they changed made it so that, the instant I updated one of my dropdown labels lists (the authors list), it disappeared. I'm going to have to experiment to see if I can bring it back.
UPDATE: Okay, following the original instructions for adding the dropdown list to my blog did not make the list reappear. FYI, the list does still exist - I can see the gadget in my Blogger layout. I'm not entirely sure what I'm going to try next, and I never got any responses to past requests for help I sent to Blogger, so I'm not hopeful I'll get any help now. My labels lists are too huge to include as anything other than dropdown lists, so I'm kind of stuck right now. Until I can figure out how to get my Authors list back, I don't plan on updating either of my remaining dropdown labels lists. Sorry for any inconvenience this causes.
YET ANOTHER UPDATE: I have no idea what I did, but I got my dropdown list back. Unfortunately, none of my author labels are selected anymore, so I have to go back and reselect everything.