This shouldn’t be happening if we’re receiving data, no. Perhaps it lost connection with the Cayenne server even if your internet connection was otherwise up and running during that time? Or it could just be a bug on our side.
Here is what I would try. Set up a trigger in Add New > Triggers to alert you via text message or email when the Arduino goes offline (from our server’s perspective, of course). If it coincides with the next time you see a gap in the graph like this, then that would be a reasonable explanation, and we can look into troubleshooting the connectivity.
If there is another gap like this and the trigger never fired to alert you that the Arduino was offline, then it’s likely an issue with our data logging, and we can investigate from that perspective.