I tested the EU-Instances and Cacti is graphing correctly for me.
There are two common issues when using Cacti to watch out for. One is that the Cacti system checks for connections once every 60 seconds or so. If you watch 45 seconds of a stream then stop the system may not log you as a viewer. The second is the graphing time range is not good about reseting to the current time. If you load the graph page and select ‘last half hour’ as your time frame it loads the current time and last half hour. But if you go to lunch and come back, even if you refresh the page the system will still have the old ‘half-hour’ times loaded. In these cases you must manually set the time frame you wish to view.
-Craig