How to verify if the Logger function has started and stopped:
You get two clues one is the power button will blink green when Logging.
Second indicator on the screen shows a Stop Recording icon, top right corner of display.
Here is what the Logger screen looks like before you start Logging.
Here is what the Logger screen looks like when it's in the middle of Logging.
Here is what the Logger screen looks like when the Logging session has met the Duration and stopped.