My Smart Power outlet is suddenly reporting negative power values

One of my smart power outlets, with which I am using a modified version of Smart Laundry Monitor has been working flawlessly for over a year. All of a sudden today I am getting spurious triggers from the app during the wash cycle.

I opened the API dashboard and looked at the log and there are negative power values in there (which will be causing the smartapp to trigger the ‘Washing Done’ alert)

Not sure why or even, how the smart power outlet can be reporting negative values, unless my washing machine has started generating it’s own power (which seems unlikely!)

ant idease anyone?