Okay, more progress: I think I've fixed I.A.D. (Irrecoverable Archive Dillemma, as defined here). At least I fixed one cause of it. It was very tricky, so perhaps there are more variables to the system. If you are experiencing this problem (i.e., some of the weeks or months you should have archives for are not showing up in the archive index list, and not getting published), you will need to reset your archives (explained below). But then, hopefully, they'll be there.