The dashboard plugin loses or more to the point freeze the voltage, temp and other raspberry pi related information after a short while but only if printing. The information will not return without a reboot of the pi and if I refresh the web browser just reads all zeros. I'm using the latest Octopi version on a pi 3b and otherwise nothing special. I can certainly live without that information and it works correctly otherwise.
Maybe you should open an issue on the plugin's issue tracker page linked here?