Post Indexer seems to be skipping indexing sites?

I have post indexer installed. I followed the steps to rebuild the index, at which time I got the 7 sites in queue message. This morning I looked and the plugin is showing that everything is complete (there's not a rebuild in queue or anything), yet on the stats there's nothing showing. Most Indexed Sites is blank, Recently Indexed Posts is blank, it looks like nothing is being done. Crons are running, as I see them in the log tab, but the posts don't seem to be indexing. At this point, I'm not sure what's going on and need some direction to help figure this out.