Chart's X-Axis Time Values are 00:00:00


I have my node-red project deployed to a raspberry pi that is not connected to the internet. I have a dashboard chart that, when a button is pressed, it populates a "1" value so that a vertical line appears on the chart. The last minute in time is set along the X axis, so the button press corresponds to the exact time.

Intermittently this works great. But recently the time values on the X-Axis are 00:00:00. Has anyone experienced this before? Is it unable to get the system time for some reason (like lack of internet connection)?

Here is what the node properties look like:



The only way to diagnose the problem is if you also post your flow here.