Luke's video is showing exactly what we are seeing as well. It is intermittent, but when it happens the chart will show one set of data and when you go to edit will show a different set of data and immediately update the chart. We're using bar charts is the only real difference.
So the Powerpoint will look fine until somebody goes to make a change (hide a set of data or go to add additional data), and suddenly all the data is wrong.
All our instances of the error (that we're aware of) were from one computer. We did an online repair on July 9th and so far haven't seen it appear again.