Usage statistics plugin displaying data for some articles but not others


I enabled Usage Statistics plugin yesterday and this morning when I’m reviewing my site, it seems that the graph of view statistics is only showing for some articles, but not others. I know for a fact that I have viewed the galleys for these articles (in fact, I did it while logged in to multiple users) and I know my mother and sister also looked at at least one of them yesterday, so I can’t imagine why the statistics aren’t showing up. And why the inconsistency between articles?

I’m running version

Thanks for any help you can offer,