I experienced the same issue while tracking my gold SQL Server tag.  I needed to reselect the bade from the tracker for it to actually update the graph.

This has been asked-and-answered at http://meta.stackexchange.com/questions/267818/next-tag-badge-panel-score-and-answers-counter-discrepancy - unfortunately, the answer is the workaround I talked about above.

I suppose since this was marked as a bug, it might get some attention in 6-8 weeks.