This is a problem that crops up a lot and has happened in many past versions of PRTG as well as the latest. Not exactly sure what the trigger is, but I think it may have to do with a sensor being paused/unpaused and/or after a probe is rebooted.
I'll try to describe it in text but I have some screen shots that make it clearer.
- problem starts with a graph (it's a sensor factory pulling data from several other sensors that are custom exexml) that is supposed to be using the "stacked" chart type. When first viewing the sensor screen, the graph is still shown with the line graph. - if you switch to the Settings tab, it shows that the "stack channels" radio button is already selected. You just press Save and return to the sensor screen. - now the graph is shown properly in stacked format.
Note that this is NOT just when a sensor is created etc, many of these sensors have been in PRTG for a long long time and over multiple versions. I've used the above process to "correct" them multiple times (very tedious...)
But at some point this crops up again, again, not sure what the trigger is. Has anyone seen this before? Thanks, Tim