For months I had the same set of "Created vs Resolved" charts, with the cumulative option being enabled, embedded in one of our confluence pages on our Atlassian OnDemand instance.

But for a couple of days now (or 1-2 weeks maybe, unsure) the charts are not showing the cumulative results anymore. However, I cannot actually click the "Edit" button in the chart's edit dialog (in the preview pane). Nothing happens.
If I copy the link of the edit button and open in a new window, I just get the same chart.

Next step I tried was to create a new "Created vs. Resolved" chart, but that only lead to an empty preview pane with a warning to fill in the details in the preview pain (sic!).
I have attached a screenshot of what that dialog looks like.

This seems to be a regression (unless it's an issue with our specific instance). Our exact version is 6.0.0-OD-2015.48.1-0006.